November 2003	Subscription Information	Volume 29 Number 11

articles

Intraocular lens power calculation after corneal refractive surgery: Double-K method
Jaime Aramberri, MD

Purpose:

To determine the accuracy of a method of calculating intraocular lens (IOL) power after corneal refractive surgery.

 

Setting:

Department of Ophthalmology, Hospital de Gipuzkoa, San Sebastián, Spain.

 

Methods:

The SRK/T formula was modified to use the pre refractive surgery K-value (Kpre) for the effective lens position (ELP) calculation and the post refractive surgery K-value (Kpost) for IOL power calculation by the vergence formula. The Kpre value was obtained by keratometry or topography and the Kpost, by the clinical history method. The formula was assessed in 9 cases of cataract surgery after laser in situ keratomileusis (LASIK) or photorefractive keratectomy (PRK) in which all relevant data were available. Refractive results of the standard SRK/T and the double-K SRK/T were compared statistically.

 

Results:

The mean IOL power for emmetropia and the achieved refraction (mean spherical equivalent [SE]), respectively, were +17.85 diopters (D) ± 3.43 (SD) and +1.82 ± 0.73 with the standard SRK/T and +20.25 ± 3.55 D and +0.13 ± 0.62 D with the double-K SRK/T. No case in the standard SRK/T group and 6 cases (66.66%) in the double-K group achieved a ±0.5 D SE.

 

Conclusion:

Double-K modification of the SRK/T formula improved the accuracy of IOL power calculation after LASIK and PRK.
 J Cataract Refract Surg 2003; 29:2063–2068 © 2003 ASCRS and ESCRS

Accommodation obtained per 1.0 mm forward movement of a posterior chamber intraocular lens
Yoshiaki Nawa, MD, Tetsuo Ueda, MD, Mieko Nakatsuka, MD, Mieko Nakatsuka, MD, Hideyuki Tsuji, MD, Hiroshi Marutani, MD, Yoshiaki Hara, MD, Hiroshi Uozato, PhD

Purpose:

To clarify the amount of accommodation per 1.0 mm forward movement of a posterior chamber intraocular lens (IOL).

 

Setting:

Department of Ophthalmology, Nara Medical University, Nara, Japan.

 

Methods:

A ray-focusing equation of pseudophakic eyes was obtained with the ray-tracing method using Mathematica^® computer software (Wolfram). At first, it was assumed that the anterior radius of curvature of the cornea was 7.7 mm, the thickness was 0.5 mm, and the refractive index was 1.3375, and an AcrySof^® IOL (Alcon) was implanted in the capsular bag. Anterior and posterior radii of curvature and IOL thickness data were provided from the manufacturer and inserted in the equation. Next, the amount of accommodation per 1.0 mm of forward movement of a posterior chamber IOL was calculated under the assumption that the axial length (AL) varied from 21.0 to 27.0 mm and the implanted IOL from 30.0 to 11.0 diopters (D). The AL was fixed at 24.0 mm, and the anterior radius of curvature was varied from 6.5 to 9.5 mm and the IOL from 10.0 to 30.0 D. Similar calculations were then performed.

 

Results:

Under the assumption of a fixed corneal anterior radius of curvature of 7.7 mm, when the AL was 24.0 mm and the implanted IOL 20.0 D, 1.0 mm of forward IOL movement corresponded to 1.3 D of accommodation. When the AL was 21.0 mm and a the IOL 30.0 D, 1.0 mm of forward IOL movement corresponded to 2.3 D of accommodation. When the AL was 27.0 mm and the IOL 11.0 D, 1.0 mm of forward IOL movement corresponded to 0.8 D of accommodation. Similarly, when the anterior radius of corneal curvature was varied from 6.5 to 9.5 mm and the IOL from 10.0 to 30.0 D and the AL was fixed at 24.0 mm, 1.0 mm of forward IOL movement corresponded to 0.5 to 1.9 D of accommodation.

 

Conclusion:

Accommodation obtained per 1.0 mm of forward IOL movement varied with AL from 0.8 D in a long eye to 2.3 D in a short eye. It also varied with the corneal power. Thus, one should not state that 1.0 mm of forward IOL movement always corresponds to a certain amount of diopters of accommodation.
 J Cataract Refract Surg 2003; 29:2069–2072 © 2003 ASCRS and ESCRS

Effect of intraocular lens implantation on visual acuity, contrast sensitivity, and depth of focus
Ying-Khay Nio, MD, Nomdo M. Jansonius, MD, PhD, Ed Geraghty, Sverker Norrby, PhD, Aart C. Kooijman, PhD

Purpose:

To determine the role of spherical and irregular aberrations in the optics of the natural eye and after intraocular lens (IOL) implantation in terms of visual acuity, contrast sensitivity, and depth of focus.

 

Setting:

Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands.

 

Methods:

Visual acuity and defocus-specific contrast sensitivity in 11 pseudophakic patients (IOL group) and 27 age-matched phakic subjects were compared. The results were obtained psychophysically. Spherical and irregular aberrations were subsequently estimated by comparing the measured myopic shift (optimum focus of contrast sensitivity at 4 cycles per degree [cpd] compared to that at 16 cpd) and depth of focus with those of theoretical eye models with varying amounts of irregular and spherical aberrations.

 

Results:

The best corrected visual acuity and best corrected contrast sensitivity in the IOL group did not significantly differ from that in the phakic group. The depth of focus was larger in the IOL group at a pupil diameter of 6.0 mm (P <.05). Comparison with theoretical eye models suggested a higher amount of spherical aberration in the IOL group; irregular aberration was almost the same in both groups.

 

Conclusion:

There was a higher amount of spherical aberration in the IOL group, related to a larger depth of focus, without loss of contrast sensitivity at optimum focus or loss of visual acuity. This might contribute to better quality of vision in pseudophakic subjects than in presbyopic phakic subjects.
 J Cataract Refract Surg 2003; 29:2073–2081 © 2003 ASCRS and ESCRS

Effect of methods of myopia correction on visual acuity, contrast sensitivity, and depth of focus
Ying-Khay Nio, MD, Nomdo M. Jansonius, MD, PhD, Robert H.J. Wijdh, MD, W. Houdijn Beekhuis, MD, Jan G.F. Worst, MD, PhD, Sverker Norrby, PhD, Aart C. Kooijman, PhD

Purpose:

To psychophysically measure spherical and irregular aberrations in patients with various types of myopia correction.

 

Setting:

Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands.

 

Methods:

Three groups of patients with low myopia correction (spectacles, soft contact lens, and Intacs) and 4 groups with high myopia correction (spectacles, rigid contact lens, Artisan claw lens, and laser in situ keratomileusis [LASIK]) had through-focus contrast sensitivity measurements to establish the myopic shift and depth of focus. From these 2 parameters, spherical and irregular aberrations were determined using theoretical eye models and geometric optics. Visual acuity, stray light, and predictability were also studied.

 

Results:

There were no differences in best corrected visual acuity (BCVA) or best corrected contrast sensitivity between the low myopia groups. The Intacs group had a significantly larger depth of focus (P <.05). The results in the soft contact lens group were comparable to those in a human eye model with an average amount of spherical and irregular aberrations. The LASIK group had worse uncorrected visual acuity (UCVA) and best corrected contrast sensitivity than the spectacles, rigid contact lens, and Artisan claw lens groups (P <.05) due to the amount of spherical and irregular aberrations present after LASIK. The low and high myopia spectacles groups had average amounts of spherical and irregular aberrations.

 

Conclusions:

Neither surgical techniques nor contact lenses resulted in BCVA or best corrected contrast sensitivity that surpassed the values measured in the best corrected spectacles groups. The Artisan claw lens performed better than LASIK in UCVA, predictability, and best corrected contrast sensitivity.
 J Cataract Refract Surg 2003; 29:2082–2095 © 2003 ASCRS and ESCRS

Spherical aberration after laser in situ keratomileusis and photorefractive keratectomyClinical results and theoretical models of etiology
Peter S. Hersh, MD, Kristen Fry, OD, J. Warren Blaker, PhD

Purpose:

To assess changes in corneal asphericity after laser refractive surgery and mathematically model possible causes of the changes.

 

Setting:

Cornea and Laser Eye Institute, Hersh Vision Group, Teaneck, New Jersey, USA.

 

Methods:

The corneal topography (EyeSys 2000) of 20 eyes was measured before and after laser in situ keratomileusis, laser-assisted subepithelial keratectomy, and photorefractive keratectomy for myopia. All preoperative and postoperative maps were analyzed using the CTView 4.0, a computer software program for determining quantitative corneal spherical aberration. To define possible mechanisms of asphericity change, 2 mathematical models of corneal ablation were constructed and theoretical postoperative corneal asphericities were determined over a range of corrections from -12.0 to +6.0 diopters. Model 1 assumes homogeneous beam fluence over the ablation zone, and model 2 accounts for a theoretical ablation rate drop off peripherally as a result of the angle of incidence of the laser beam on the cornea. Postoperative clinical corneal spherical aberration was compared to the theoretically predicted asphericity values.

 

Results:

After excimer laser procedures, all corneas had positive asphericity within the ablation zone, generally changing from a prolate to an oblate optical contour. The mean asphericity (Q) was -0.17 ± 0.14 (SD) preoperatively and +0.92 ± 0.70 postoperatively. The mean change in spherical aberration was +1.09 ± 0.67 of positive asphericity; the range of asphericity change was +0.40 to +2.73 in the direction of a more oblate corneal profile. A trend toward greater change in asphericity and more oblateness was observed among eyes receiving higher correction. A mathematical model taking into account theoretical beam fluence changes across the ablation zone was highly predictive of the actual postoperative asphericity measurements.

 

Conclusions:

The cornea within the ablation zone becomes more oblate after laser refractive surgery. A mathematical model of the change in asphericity, which accounts for the angle of incidence of the laser beam across the ablation area, predicted this change in spherical aberration. If the model is correct, possible changes in laser algorithms, delivering more ablation to the peripheral optical zone, may better retain the native corneal prolate conformation. Moreover, wavefront-guided ablations may have to consider the effects of fluence variability across the optical zone to fully correct spherical as well as other aberrations.
 J Cataract Refract Surg 2003; 29:2096–2104 © 2003 ASCRS and ESCRS

Laser-assisted subepithelial keratectomy and photorefractive keratectomy for the correction of hyperopiaResults of a 2-year follow-up
Rudolf Autrata, MD, PhD, Jaroslav Rehurek, MD, PhD

Purpose:

To evaluate and compare the efficacy, safety, predictability, and stability of laser-assisted subepithelial keratectomy (LASEK) and photorefractive keratectomy (PRK) for low to moderate hyperopia with a 2-year follow-up.

 

Setting:

Department of Ophthalmology, Masaryk University Hospital, Brno, Czech Republic.

 

Methods:

This prospective comparative single-surgeon study included 216 eyes of 108 patients with hyperopia who received PRK in 1 eye and LASEK in the contralateral eye. The mean patient age was 38.3 years (range 25 to 58 years). The mean preoperative spherical equivalent (SE) cycloplegic refraction was +3.67 diopters (D) ± 1.15 (SD) (range +2.00 to +5.00 D), and astigmatism was less than 1.00 D. In each patient, PRK was performed in 1 eye (Group A) and LASEK was performed in the other eye (Group B) using the Nidek EC-5000 excimer laser. Postoperative uncorrected visual acuity (UCVA), best corrected visual acuity, contrast sensitivity, manifest and cycloplegic refractions, refractive stability and predictability, postoperative pain, and corneal haze were examined and statistically analyzed. A P value less than 0.05 was considered significant.

 

Results:

At 1 week, the UCVA was 20/40 or better in 58% of PRK eyes and 85% of LASEK eyes (P =.037); at 2 years, it was 20/40 or better in 81% and 91%, respectively (P =.076). At 2 years, the UCVA for near was N8 or better in 73% of PRK eyes and 89% of LASEK eyes (P =.064). No patient lost 2 or more lines of Snellen visual acuity. The safety index was 1.03 in PRK eyes and 1.08 in LASEK eyes. Refractive stability was achieved at 6 months in LASEK eyes and at 12 months in PRK eyes. The mean SE cycloplegic refraction decreased from +3.58 D (PRK eyes) and +3.76 D (LASEK eyes) at baseline to +0.74 D and +0.32 D, respectively, at 2 years; in 57% and 78% of eyes, respectively, the refraction was within ±0.50 D of the targeted refraction. Peripheral corneal haze scores at 3 to 9 months and pain scores at 1 to 3 days were significantly lower in the LASEK group than in the PRK group.

 

Conclusions:

Laser-assisted subepithelial keratectomy for hyperopia up to +5.00 D provided good visual and refractive results. It significantly reduced postoperative pain, grade of peripheral ring-shaped corneal haze, and regression of hyperopia. Hyperopic LASEK provided quicker visual recovery and achieved better efficacy, predictability, and refractive stability than hyperopic PRK.
 J Cataract Refract Surg 2003; 29:2105–2114 © 2003 ASCRS and ESCRS

Anterior chamber depth in relation to refractive status measured with the Orbscan II Topography System
Tanja M. Rabsilber, MD, Klio A. Becker, MD, Inez B. Frisch, MD, Gerd U. Auffarth, MD

Purpose:

To evaluate the anterior chamber depth (ACD) according to refractive status, assess the reliability of repeated ACD measurements using the Orbscan II Topography System (Bausch & Lomb), compare Orbscan II and IOLMaster (Carl Zeiss Meditec AG) ACD measurements, and investigate the correlation between refraction, axial length (AL), and ACD.

 

Setting:

Department of Ophthalmology, Ruprecht-Karls-University of Heidelberg, Heidelberg, Germany.

 

Methods:

In this clinical study, 60 patients with a mean age of 43.8 years ± 18.74 (SD) were assigned to 1 of 3 groups of 20 patients each according to refraction: emmetropia group; hyperopia group (mean +4.84 ± 1.60 diopters [D]); myopia group (mean –9.64 ± 3.79 D). Using the Orbscan II system, 3 consecutive ACD measurements (apex and 3.0 mm zone) were performed. The IOLMaster was used to measure ACD and AL.

 

Results:

The mean ACD (from epithelium) with the Orbscan II and IOLMaster, respectively, was 3.61 ± 0.24 mm and 3.61 ± 0.24 mm in the emmetropia group, 3.03 ± 0.21 mm and 3.06 ± 0.24 mm in the hyperopia group, and 3.72 ± 0.26 mm and 3.73 ± 0.23 mm in the myopia group. The standard deviation of the repeated Orbscan II measurements increased from 13 to 15 μm from the apex to the 3.0 mm zone. The difference between the apex and 3.0 mm zone of the cornea in all groups ranged from 0.1 to 0.12 mm. The mean AL was 23.52 ± 0.82 mm in the emmetropia group, 22.14 ± 0.64 mm in the hyperopia group, and 27.44 ± 1.67 mm in the myopia group. There was a significant correlation between the spherical equivalent and AL (r = 0.94).

 

Conclusion:

Significantly lower ACD values were found in the hyperopia group than in the other 2 groups. There was no difference in ACD between the emmetropia and myopia groups even though the AL in the myopia group was 4.0 mm longer. No statistical difference in ACD measurements was found between the Orbscan II and IOLMaster.
 J Cataract Refract Surg 2003; 29:2115–2121 © 2003 ASCRS and ESCRS

Determining postoperative anterior chamber depth
Katharina Kriechbaum, MD, Oliver Findl, MD, Paul Rolf Preussner, MD, PhD, Christina Köppl, MD, Jochen Wahl, MD, Wolfgang Drexler, PhD

Purpose:

To compare measured and calculated postoperative anterior chamber depths (ACDs).

 

Setting:

Department of Ophthalmology and Institute of Medical Physics, University of Vienna, Vienna, Austria, and Department of Ophthalmology, University of Mainz, Mainz, Germany.

 

Methods:

The postoperative ACD was measured in 189 pseudophakic eyes using a laboratory prototype of partial coherence interferometry (PCI). In 6 intraocular lens (IOL) groups, the mean ACD was calculated by ray tracing based on the best-known A-constants of the SRK formulas. In addition, for each IOL type, each measured ACD was compared with a value calculated using the individual spherical equivalent of the postoperative refraction.

 

Results:

The measured and the calculated ACD values were close and did not show systematic differences. The ACD values obtained in the study, however, differed significantly from the values published by the IOL manufacturers. A comparison of the PCI-assessed ACDs and the calculated values using the postoperative refraction showed more scattered results for the refraction-based data, which was probably the result of higher measurement errors with the autorefractometer than with PCI.

 

Conclusions:

High-precision interferometry measurements and ray-tracing calculations confirmed each other. The resulting mean ACD values should be used instead of the manufacturers' values. The refractive outcome of cataract surgery can be improved by combining preoperative high-precision PCI biometry and numerical ray tracing for IOL power calculations.
 J Cataract Refract Surg 2003; 29:2122–2126 © 2003 ASCRS and ESCRS

Capsule measuring ring to predict capsular bag diameter and follow its course after foldable intraocular lens implantation
Mana Tehrani, MD, H. Burkhard Dick, MD, Frank Krummenauer, PhD, Gudrun Pfirrmann, Thomas Boyle, MD, Bernhard M. Stoffelns, MD

Purpose:

To evaluate the extent of capsular bag shrinkage after cataract surgery with intraocular lens (IOL) implantation and develop a regression formula to predict postoperative capsular bag size.

 

Setting:

Eye Hospital, Johannes Gutenberg-University, Mainz, Germany.

 

Methods:

The axial length (AL), anterior chamber depth, and corneal radius in 58 eyes were measured preoperatively. Cataract surgery was by phacoemulsification followed by implantation of a 3-piece, acrylic, posterior chamber IOL. The capsular bag diameter and anterior capsulorhexis were measured intraoperatively and 1 day and 1, 3, and 6 months postoperatively using a Koch capsule measuring ring (HumanOptics).

 

Results:

The mean capsular bag size was 10.53 mm intraoperatively, 10.31 mm at 1 day, 9.62 mm at 1 month, 9.07 mm at 3 months, and 9.01 mm at 6 months. The mean capsular bag shrinkage over the entire postoperative period was 14.8% ( P <.001). Of the parameters studied, only AL had a positive correlation with capsule shrinkage. The correlation was moderate but statistically significant ( P =.001).

 

Conclusions:

A correlation was found between capsular bag shrinkage and AL. Using preoperative biometric data, a regression formula of moderate validity was determined to predict capsular bag shrinkage.
 J Cataract Refract Surg 2003; 29:2127–2134 © 2003 ASCRS and ESCRS

Visual functional outcomes of cataract surgery in the United States, Canada, Denmark, and Spain
Report of the International Cataract Surgery Outcomes Study
Jens Christian Norregaard, MD, PhD, Peter Bernth-Petersen, MD, PhD, Jordi Alonso, MD, PhD, Tavs Folmer Andersen, MSc, PhD, Gerard F. Anderson, PhD

Purpose:

To compare functional outcomes after cataract surgery performed at 4 sites in 4 countries that have been described as having significant differences in the organization of care and patterns of clinical practice.

 

Setting:

Multicenter cohort study from the United States, Canada, Denmark, and Spain.

 

Methods:

Clinical data and patient interview data were collected preoperatively and 4 months postoperatively. Functional outcomes were assessed by the Visual Function Index (VF-14), a self-reported measure of visual function. Scores on the VF-14 range from 0 (maximum impairment) to 100 (no impairment).

 

Results:

Unilateral surgery was performed in 1073 patients. In this subgroup, the odds of achieving an optimal functional outcome (VF-14 score ≥95) were similar among sites after controlling for differences in case mix. Bilateral surgery was performed in 211 patients. A postoperative visual acuity of 0.50 or better in both eyes was reported in 155 patients. However, 37% of these patients reported visual function impairment (VF-14 score <95).

 

Conclusions:

A previously identified variation in treatment modalities among the 4 sites did not have a significant effect on the odds of achieving an optimal functional outcome. In addition to visual acuity measurements, the VF-14 index provides information on functional outcomes that is useful, especially in studies assessing the benefits of cataract surgery in a public health care setting.
 J Cataract Refract Surg 2003; 29:2135–2142 © 2003 ASCRS and ESCRS

Early objective assessment of intraocular inflammation after phacoemulsification cataract surgery
Oliver Findl, MD, Michael Amon, MD, Vanessa Petternel, MD, Andreas Kruger, MD

Purpose:

To evaluate the time course of blood–aqueous barrier (BAB) disturbance in the early period after small-incision cataract surgery.

 

Setting:

Department of Ophthalmology, Vienna University, Vienna, Austria.

 

Methods:

In a prospective study, 15 eyes of 15 patients with age-related cataract had small-incision cataract surgery by phacoemulsification with intraocular lens implantation. Care was taken to minimize trauma to the uvea during surgery. Postoperative inflammation was assessed by measuring aqueous flare and cell count with a laser flare–cell meter. Postoperative measurements were performed hourly for the first 6 hours, every 2 hours until 12 hours, every 4 hours until 40 hours, and every 8 hours until 56 hours.

 

Results:

The time course of aqueous flare and cell count differed significantly among patients. The peak inflammatory response in most cases was 1 hour after surgery, with the response decreasing thereafter. The pattern of the time course was classified into subgroups defined by the presence and size of an initial spike immediately after surgery and the intensity of the subsequent inflammatory reaction. A slight increase in flare and cells was seen in the morning hours of the first postoperative day.

 

Conclusions:

Acute BAB disturbance within the first 48 hours after small-incision cataract surgery showed high interpatient variability. However, many differences were not detectable 1 day after surgery.
 J Cataract Refract Surg 2003; 29:2143–2147 © 2003 ASCRS and ESCRS

Cumulative probability of neodymium: YAG laser posterior capsulotomy after phacoemulsification
Hiroshi Ando, MD, Nobuyo Ando, MD, Tetsuro Oshika, MD

Purpose:

To retrospectively analyze the cumulative probability of neodymium:YAG (Nd:YAG) laser posterior capsulotomy after phacoemulsification and to evaluate the risk factors.

 

Setting:

Ando Eye Clinic, Kanagawa, Japan.

 

Methods:

In 3997 eyes that had phacoemulsification with an intact continuous curvilinear capsulorhexis, the cumulative probability of posterior capsulotomy was computed by Kaplan-Meier survival analysis and risk factors were analyzed using the Cox proportional hazards regression model. The variables tested were sex; age; type of cataract; preoperative best corrected visual acuity (BCVA); presence of diabetes mellitus, diabetic retinopathy, or retinitis pigmentosa; type of intraocular lens (IOL); and the year the operation was performed. The IOLs were categorized as 3-piece poly(methyl methacrylate) (PMMA), 1-piece PMMA, 3-piece silicone, and acrylic foldable.

 

Results:

The cumulative probability of capsulotomy after cataract surgery was 1.95%, 18.50%, and 32.70% at 1, 3, and 5 years, respectively. Positive risk factors included a better preoperative BCVA ( P =.0005; risk ratio [RR], 1.7; 95% confidence interval [CI], 1.3-2.5) and the presence of retinitis pigmentosa ( P <.0001; RR, 6.6; 95% CI, 3.7-11.6). Women had a significantly greater probability of Nd:YAG laser posterior capsulotomy ( P =.016; RR, 1.4; 95% CI, 1.1-1.8). The type of IOL was significantly related to the probability of Nd:YAG laser capsulotomy, with the foldable acrylic IOL having a significantly lower probability of capsulotomy. The 1-piece PMMA IOL had a significantly higher risk than 3-piece PMMA and 3-piece silicone IOLs.

 

Conclusions:

The probability of Nd:YAG laser capsulotomy was higher in women, in eyes with a better preoperative BCVA, and in patients with retinitis pigmentosa. The foldable acrylic IOL had a significantly lower probability of capsulotomy.
 J Cataract Refract Surg 2003; 29:2148–2154 © 2003 ASCRS and ESCRS

Combined endoscopic erbium: YAG laser goniopuncture and cataract surgery
Nicolas Feltgen, MD, Heiko Mueller, MD, Beat Ott, PhD, Martin Frenz, PhD, Jens Funk, MD, PhD

Purpose:

To study the safety and efficacy of endoscopic erbium:YAG (Er:YAG) laser goniopuncture combined with cataract surgery to treat glaucoma.

 

Setting:

Department of Ophthalmology, Albert-Ludwigs-University Freiburg, Freiburg, Germany, and Institute of Applied Physics, University of Bern, Bern, Switzerland.

 

Methods:

In this nonrandominized clinical trial, 20 eyes of 20 patients with cataract and glaucoma were treated by combined phacoemulsification and Er:YAG goniopuncture. The primary study endpoints were intraocular pressure (IOP), visual acuity, and number of antiglaucoma drugs 1 year after surgery. Two- and 3-year postoperative data were also measured. This prospective treatment arm was compared to a retrospective inclusion-matched control group treated by cataract surgery alone.

 

Results:

The mean IOP dropped by 30% (23.5 mm Hg ± 3.9 [SD] to 16.3 ± 2.7 mm Hg) after 12 months in the laser-treated group ( P <.0001) and by 9% (19.8 ± 1.3 mm Hg to 18.1 ± 1.8 mm Hg) in the control group ( P =.12). After 3 years, the mean IOP in the laser group was 15.0 ± 2.0 mm Hg. The mean number of antiglaucoma drugs needed decreased from 1.6 ± 0.9 to 0.5 ± 0.8 in the laser group ( P <.0001) and from 1.0 ± 0.9 to 0.8 ± 0.9 in the control group ( P =.21). Anterior chamber hemorrhage occurred in 12 eyes after laser treatment and resolved within 72 hours in all but 1 patient who was on warfarin sodium (Coumadin ® ) therapy. There were no cases of hypotony in either group.

 

Conclusions:

Endoscopic Er:YAG laser goniopuncture was a successful adjunct to cataract surgery in glaucoma patients. Sustained IOP reduction was achieved with few postoperative complications.
 J Cataract Refract Surg 2003; 29:2155–2162 © 2003 ASCRS and ESCRS

Group IIA phospholipase A₂ content in tears of patients having photorefractive keratectomy
Valtteri V. Aho, MD, Juha M. Holopainen, MD, Timo Tervo, MD, Jukka A.O. Moilanen, MD, Timo Nevalainen, MD, K. Matti Saari, MD

Purpose:

To study the effect of photorefractive keratectomy (PRK) on the concentration of group IIA phospholipase A₂ (GIIAPLA₂) in tears.

 

Setting:

Departments of Ophthalmology and Pathology, University of Turku, Turku, and Helsinki University Eye Hospital, Helsinki, Finland.

 

Methods:

Tear samples were collected from 25 eyes of 23 patients (mean age 32.3 years ± 8.6 [SD]) preoperatively and 2 and 7 days after PRK. The GIIAPLA₂ concentration in the tears was measured by time-resolved fluoroimmunoassay.

 

Results:

The GIIAPLA₂ concentration was significantly lower and the tear fluid flow rate significantly higher 2 days after PRK than preoperatively. At 7 days, the GIIAPLA₂ concentration and the tear fluid flow-corrected excretion of GIIAPLA₂ were significantly higher than preoperatively and at 2 days. The tear flow rate was also significantly higher than preoperatively.

 

Conclusions:

The GIIAPLA₂ content in tears decreased 2 days after PRK due to dilution of the GIIAPLA₂ content during hypersecretion of reflex tears. Photorefractive keratectomy caused an increase in the tear flow rate, GIIAPLA₂ concentration, and tear fluid flow-corrected excretion of GIIAPLA₂ in tears 7 days after surgery, enhancing the protection of tears against bacterial infections.
 J Cataract Refract Surg 2003; 29:2163–2167 © 2003 ASCRS and ESCRS

Black diaphragm intraocular lens implantation in aphakic eyes with traumatic aniridia and previous pars plana vitrectomy
Xiaoguang Dong, MD, Bin Yu, MD, Lixin Xie, MD

Purpose:

To evaluate the efficacy of secondary black diaphragm intraocular lens (IOL) implantation in aphakic eyes with traumatic aniridia and previous pars plana vitrectomy (PPV).

 

Setting:

Shandong Eye Institute and Hospital, Qingdao, China.

 

Methods:

This retrospective study comprised 15 aphakic eyes with aniridia and no vitreous that had implantation of a secondary black diaphragm IOL 6 to 72 months after PPV. The PPV was performed as a result of trauma to the posterior segment. Before implantation of the IOL, all patients had reduced visual acuity from aphakia and intolerable glare from aniridia. Eyes were aphakic as a result of previous extracapsular cataract extraction (1 eye), lens extrusion during trauma (3 eyes), or simultaneous cataract lensectomy during PPV (11 eyes). Significant iris defects were present, with 9 eyes being aniridic after the injury. The mean follow-up was 17 months (range 3 to 34 months). The postoperative visual acuity, intra- ocular pressure (IOP), endothelial cell density, IOL centration, and intraocular inflammation were monitored.

 

Results:

All 15 eyes had improved visual acuity and marked glare reduction after IOL implantation. No major IOL decentration was seen. Five patients had increased IOP 3 to 5 days after IOL implantation; 3 were known to have secondary glaucoma from trauma before surgery and their IOP was controlled preoperatively (< 21 mm Hg) with timolol 0.5% eyedrops. The other 2 patients had normal- appearing angles, and 1 was diagnosed with hemolytic glaucoma after IOL insertion. Postoperative elevated IOP was controlled by timolol eyedrops (4 eyes) or selective laser trabeculoplasty (1 eye). Hyphema was seen in 1 patient on the first day after IOL implantation, but no further bleeding was noted. Vitreous hemorrhage was seen the first day after IOL insertion in 2 patients. One resolved without sequelae; the other required vitreous washout. Retinal detachment and cystoid macular edema did not occur in any patient.

 

Conclusions:

Black diaphragm IOL implantation can be considered in eyes with coexisting aphakia and aniridia and without vitreous. Intraoperative IOP regulation is crucial in vitrectomized eyes to prevent complications such as expulsive hemorrhage. In general, visual function was better after IOL insertion as a result of better visual acuity and glare reduction. Although this IOL appears to be safe, long-term results must be assessed in studies with a longer follow-up and a larger study group.
 J Cataract Refract Surg 2003; 29:2168–2173 © 2003 ASCRS and ESCRS

Elliptical ELSA (LASEK) instruments for the treatment of astigmatism
Chris P. Lohmann, MD, PhD, Christoph Winkler von Mohrenfels, MD, Wolfgang Herrmann, MD, Bernhard Gabler, MD, Thomas Laube, MD, John Marshall, PhD

Purpose:

To investigate newly designed, elliptical ELSA (excimer laser subepithelial ablation) instruments for the treatment of astigmatism.

 

Setting:

University Eye Clinic Regensburg, Regensburg, Germany, and the Rayne Institute, Department of Ophthalmology, St. Thomas' Hospital, London, United Kingdom.

 

Methods:

The new ELSA instrument set consists of an elliptical microtrephine (11.0 mm × 8.0 mm) with a 70 μm calibrated blade and an elliptical alcohol cone (11.5 mm × 8.5 mm). With this instrument set, ELSA (the laser-assisted subepithelial keratectomy [LASEK] described by Camellin) was performed in 34 astigmatic eyes. The cylindrical correction was between 1.00 diopters (D) and 3.50 D and the spherical correction, between -0.75 D and -8.75 D. In all eyes, the follow-up was 6 months. The postoperative refractive outcome was analyzed using Alpins vector analysis.

 

Results:

Excimer laser subepithelial ablation was performed without intraoperative complications in all eyes. At 6 months, the mean spherical correction was -0.04 D ± 0.27 (SD) (range +0.75 to -0.75 D) and the mean cylindrical correction, 0.27 ± 0.23 D (range 0 to 0.75 D). The mean index of success was 0.18 ± 0.15.

 

Conclusions:

With the elliptical instruments, ELSA was an effective and safe surgical procedure for astigmatism.
 J Cataract Refract Surg 2003; 29:2174–2180 © 2003 ASCRS and ESCRS

Long-term evaluation of hyperopic laser in situ keratomileusis
David Zadok, MD, Frederick Raifkup, MD, David Landau, MD, Joseph Frucht-Pery, MD

Purpose:

To evaluate the efficacy, safety, and predictability of hyperopic laser in situ keratomileusis (H-LASIK).

 

Setting:

Departments of Ophthalmology, Hadassah University Hospital, Jerusalem, and Assaf Harofeh Medical Center, Zerifin, Israel.

 

Methods:

This prospective noncomparative case series studied the results of H-LASIK in the first 92 consecutive eyes of 50 patients with up to +10.25 diopters (D) of hyperopia. For analysis, the patients were divided into 3 groups based on preoperative hyperopia: low hyperopia (<+3.00 D), moderate hyperopia (≥+3.00 to 6.00 D), and high hyperopia (≥+6.00 D).

 

Results:

Forty-two patients, 77 eyes (83.7%), were followed for at least 12 months. At 12 months, the mean manifest spherical equivalent was +0.33 ± 0.65 D (93.1% of eyes within ±1.0 D of the intended correction) in the low myopia group, +0.21 ± 0.60 D (92.3% within ±1.0 D of the intended correction) in the moderate hyperopia group, and +1.62 ± 1.50 D (36.4% within ±1.0 D of the intended correction) in the high hyperopia group. The uncorrected visual acuity (UCVA) was 20/40 or better in all eyes (100%), 24 eyes (92.3%), and 13 eyes (59.1%) in the low, moderate, and high hyperopia groups, respectively. Comparing the UCVA at the last examination with the best corrected visual acuity (BCVA) before surgery in all patients showed that 59 eyes (76.6%) were within ±1 line and 18 eyes (23.4%) were within ±2 or more lines of the preoperative BCVA. Three eyes (3.9%) in the high hyperopia group lost 2 or more lines of BCVA. Three eyes (3.9%) had flap- related complications. Eight patients (15 eyes) with a follow-up less than 12 months did not have intraoperative or postoperative complications.

 

Conclusion:

Laser in situ keratomileusis was a safe, effective, and predictable procedure for hyperopia up to +6.0 D and less predictable for higher hyperopia.
 J Cataract Refract Surg 2003; 29:2181–2188 © 2003 ASCRS and ESCRS

Actual and intended refraction after cataract surgery
Stephen B. Kaye, MD

Purpose:

To demonstrate an analytical method to compare the actual and intended refraction after cataract surgery that allows incorporation of refractive surgical effects.

 

Setting:

Corneal and External Eye Disease Service, Royal Liverpool University Hospital, Liverpool, United Kingdom.

 

Methods:

The actual postoperative refraction was compared to the intended postoperative refraction before and after removal of surgically induced changes in keratometry; that is, the keratometric surgical effect. Application of hypothesis testing is demonstrated using a standardized method of analyzing refractive data; that is, refractive data transformed into the refractive power matrix with calculation of the mean and variance–covariance of the data.

 

Results:

The method of analysis demonstrated how surgically induced changes in refractive components can be incorporated into hypothesis testing when comparing intended and actual postoperative refractions.

 

Conclusion:

Application of the standardized method of analyzing refractive data allows a more accurate evaluation of methods or formulas used to calculate intraocular lens power in cataract surgery.
 J Cataract Refract Surg 2003; 29:2189–2194 © 2003 ASCRS and ESCRS

Contact versus immersion biometry of axial length before cataract surgery
Michael P. Hennessy, FRANZCO, Derek G. Chan, MBBS

Purpose:

To compare the repeatability and agreement of contact and immersion ultrasound (US) biometry of axial length.

 

Setting:

Prince of Wales Hospital, Sydney, Australia.

 

Methods:

This prospective stratified randomized study comprised 36 patients with a preoperative refractive error less than 4.00 diopters (D) sphere or 2.00 D cylinder who were recruited before cataract surgery. Each of 3 operators measured both eyes of 12 patients by contact and immersion US techniques. A repeat measurement by both techniques was performed by the same operator in 6 cases and by a different operator in the other 6. Repeat and operator effects were examined.

 

Results:

The mean and standard deviation of the measurement sets were compared, and the differences between repeat measures were calculated. Axial length measurement was longer with the contact method than with immersion by 0.03 mm ( P =.04). The repeatability of the 2 techniques was similar.

 

Conclusions:

When the measurement set was repeated, the precision of contact US biometry was comparable to that of immersion, with no clinically significant difference in mean axial length measurements.
 J Cataract Refract Surg 2003; 29:2195–2198 © 2003 ASCRS and ESCRS