Terry Couper

Outcomes of laser refractive surgery for myopia.

Many advances have been made in laser refractive surgery, and this review examines how they have affected treatment outcomes in individuals with varying degrees of myopia (law, moderate, and high). Studies with a minimum follow-up of 1 year with at least 2 of the 3 major outcome measures--efficacy, stability, and safety--were reviewed, and how the findings were affected by differences in ethnicity was assessed.

Comparison of laser in situ keratomileusis and photorefractive keratectomy for the correction of myopia of -6.00 diopters or less

PURPOSE To evaluate the safety and efficacy of laser in situ keratomileusis (LASIK) compared to photorefractive keratectomy (PRK) for the correction of low or moderate myopia (-0.50 to -6.00 D) at 6 months after surgery. METHODS The study population comprised a non-randomized consecutive series of 622 eyes of 392 patients who were treated with the Nidek EC-5000 excimer laser. LASIK was performed using the ACS Chiron microkeratome on 314 eyes and surface PRK on 308 eyes. All patients were treated using a standard protocol, then assessed at 1, 3, and 6 months postoperatively. RESULTS Forty-four percent of the LASIK group and 67% of the PRK group attended their 6-month examination. Eighty percent of patients (111 eyes) after LASIK and 65% (136 eyes) after PRK had an uncorrected visual acuity of 20/20 or better. Spherical equivalent refraction was within +/-0.50 D of intended refraction in 78% (109 eyes) for LASIK and 82% (170 eyes) for PRK. Loss of two more lines of best spectacle-corrected visual acuity at 6 months occurred in 1.4% (2 eyes) of the LASIK group and 1.0% (2 eyes) of the PRK group. CONCLUSION At 1 month follow-up, the percentage of eyes that achieved 20/20 uncorrected visual acuity was greater in the LASIK group than in the PRK group. At 6 months, visual and refractive outcomes of LASIK and PRK were similar. Although flap related complications occurred only after LASIK, the overall risk of loss of best spectacle-corrected visual acuity was not significantly greater than for PRK.

Vision-related Quality of Life Comparison for Emmetropes, Myopes After Refractive Surgery, and Myopes Wearing Spectacles or Contact Lenses

PURPOSE To compare the vision-related quality of life among emmetropes, myopes who had refractive surgery, and myopes who wore spectacles and/or contact lenses. METHODS This cross-sectional study assessed vision-related quality of life using the Vision Quality of Life Index. Participants were age 18 years or older with a presenting visual acuity of 20/40 or better and no other ocular pathology. Responses were compared among three groups: emmetropes (spherical equivalent [SE] < 0.50 to > -0.50 diopters [D]), myopes (SE < or = -0.50 D) who wore spectacles and/or contact lenses, and myopes who had refractive surgery. RESULTS The study population included 64 emmetropes, 66 myopes who wore spectacles and/or contact lenses, and 65 myopes who had refractive surgery. No significant differences were found between the refractive surgery and emmetropic groups. In contrast, the spectacle and/or contact lens group had significantly increased odds of having concerns about injuring themselves (odds ratio = 11.5, 95% confidence interval [CI] 2.3, 57.1), difficulties coping with demands in life (odds ratio = 23.6, 95% CI 23.8, 198.1), difficulties fulfilling roles (odds ratio = 5.6, 95% CI 1.4, 22.1), and less confidence joining in everyday activities (odds ratio = 30.6, 95% CI 3.2, 292.3) compared to emmetropes. CONCLUSIONS Myopia corrected with spectacles or contact lenses had a negative impact on some areas of vision-related quality of life. However, individuals with myopia who had refractive surgery enjoyed the same vision-related quality of life as those with emmetropia. The potential improvement in vision-related quality of life should be considered when recommending treatment for myopia.

Long-term refractive outcomes and stability after excimer laser surgery for myopia

PURPOSE: To evaluate the long‐term refractive outcomes of photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) for myopia. SETTING: Centre for Eye Research Australia, Melbourne, Australia. DESIGN: Comparative case series. METHODS: Preoperative baseline refractions in eyes having PRK, LASIK, or both at 1 multisurgeon center were analyzed from patient databases. Two‐ to 13‐year follow‐up data were analyzed and compared with 1‐month postoperative visual outcomes. RESULTS: The study evaluated 389 eyes (229 patients). In the PRK group, the mean preoperative spherical equivalent (SE) was −4.05 diopters (D) ± 1.17 (SD) in eyes with low to moderate myopia and −7.97 ± 2.00 D in eyes with high myopia (P = .009) and in the LASIK group, −3.98 ± 1.27 D and −7.64 ± 1.66 D, respectively (P = .008). At the last visit, the mean SE in the PRK group was −0.64 ± 0.83 D in eyes with low to moderate myopia and −1.06 ± 1.74 D in eyes with high myopia (P = .73) and in the LASIK group, −0.33 ± 0.59 D and −0.63 ± 0.90 D, respectively (P = .68). At the end of the study, 45.9% of eyes with low to moderate myopia and 25.0% with high myopia in the PRK group and 64.8% and 37.3%, respectively, in the LASIK group were within ±0.50 D of the attempted correction. CONCLUSIONS: Laser refractive surgery effectively treated all levels of myopia. Refractive stability was achieved within 1 year postoperatively, with LASIK showing better stability than PRK for up to 6 to 9 years. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Methodology and recruitment of probands and their families for the Genes in Myopia (GEM) Study.

Purpose: Myopia is considered to be a complex disease involving both environmental and genetic factors. The Genes in Myopia (GEM) Study aims to recruit probands with myopia and their family members to allow genetic analysis of myopia to be undertaken. The purpose of this paper is to describe the methodology and recruitment of probands and families for the GEM Study. Methods: In a sample-based prospective study, 2,095 probands with myopia of −0.50 DS or worse and a positive family history of myopia were contacted via the Melbourne Excimer Laser Group (MELG) database. Probands and family members recruited into the study undertook a detailed assessment including questionnaire, best-corrected visual acuity, objective and subjective refraction, axial length, anterior chamber depth, keratometry readings, slit-lamp examination, height, weight and head circumference measurements, and blood sample collection for DNA analysis. Results: 280 probands with myopia have been recruited into the GEM Study. Probands had a mean age of 49.33 yrs. (SD +/− 11.64) with the average age of myopia onset being 12.58 years (SD +/− 6.71). The average spherical-component refractive error was: right eye −5.13 DS (SD +/− 3.06) and left eye −5.14 DS (SD +/− 3.16). Probands with extreme myopia (−10 DS or worse) showed the highest study participation rate of 56%, when compared to high (−5 DS < −10 DS) (20%), moderate (−3 DS < − 5 DS) (18%) and low myopia (−0.5 DS < −3 DS) (10%). A total of 279 out of 505 (55%) additional family members recruited were also found to be myopic. Conclusions: The GEM study has used a targeted approach to identify an Australian cohort with a diverse spread of myopia, ranging from low to extreme. Recruitment of probands via the use of an excimer laser practice has proved to be an efficient and economic means of identifying probands with a family history of myopia. In addition, the participation rate in the study appears to vary reflecting a probands perception of disease severity.

Evaluation of iris recognition system for wavefront-guided laser in situ keratomileusis for myopic astigmatism

PURPOSE: To evaluate the visual and refractive outcomes of wavefront‐guided laser in situ keratomileusis (LASIK) using an iris recognition system for the correction of myopic astigmatism. SETTING: Centre for Eye Research Australia, Melbourne Excimer Laser Research Group, and Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia. METHODS: A comparative analysis of wavefront‐guided LASIK was performed with an iris recognition system (iris recognition group) and without iris recognition (control group). The main parameters were uncorrected visual acuity (UCVA), best spectacle‐corrected visual acuity, amount of residual cylinder, manifest spherical equivalent (SE), and the index of success using the Alpins method of astigmatism analysis 1 and 3 months postoperatively. A P value less than 0.05 was considered statistically significant. RESULTS: Preoperatively, the mean SE was −4.32 diopters (D) ± 1.59 (SD) in the iris recognition group (100 eyes) and −4.55 ± 1.87 D in the control group (98 eyes) (P = .84). At 3 months, the mean SE was −0.05 ± 0.21 D and −0.20 ± 0.40 D, respectively (P = .001), and an SE within ±0.50 D of emmetropia was achieved in 92.0% and 85.7% of eyes, respectively (P = .07). At 3 months, the UCVA was 20/20 or better in 90.0% and 76.5% of eyes, respectively. A statistically significant difference in the amount of astigmatic correction was seen between the 2 groups (P = .00 and P = .01 at 1 and 3 months, respectively). The index of success was 98.0% in the iris recognition group and 81.6% in the control group (P = .03). CONCLUSION: Iris recognition software may achieve better visual and refractive outcomes in wavefront‐guided LASIK for myopic astigmatism.

Changes in Corneal Topography After Laser in situ Keratomileusis for Myopia

OBJECTIVE To define qualitative patterns of corneal topography after excimer laser in situ keratomileusis (LASIK) and to assess whether epithelial hyperplasia occurred after LASIK. METHODS A consecutive series of 18 myopic eyes of 10 patients having refractive surgery in an academic practice at the Royal Victorian Eye and Ear Hospital, Melbourne, Australia was followed prospectively after LASIK. Four eyes were treated with the VISX 20/20 excimer laser and 14 eyes were treated with the Nidek EC5000 excimer laser. Videokeratography was performed on each eye at 1, 3, and 6 months after surgery. The common digital subtraction topographic patterns were classified and used to speculate whether epithelial hyperplasia occurred. RESULTS After LASIK, 83% of subtraction maps at 1 month and 81% at both 3 and 6 months showed steepening in the ablation zone. There was no clear correlation between the topographic maps and spectacle-corrected visual acuity or regression of the initial effect after surgery. CONCLUSION Corneal topographic changes similar to those seen after photorefractive keratectomy (PRK) occur after LASIK for myopia.

Three Multizone Photorefractive Keratectomy Algorithms for Myopia

OBJECTIVE To compare the efficacy and complications of three different excimer laser algorithms for multizone photorefractive and photoastigmatic keratectomy. METHODS Three different software algorithms were applied to treat myopia and myopic astigmatism with the VISX 20/20 excimer laser. Each algorithm had a maximum ablation zone of 6 mm but differed in the number of zones employed, the proportion of the total treatment allocated to each ablation zone, and the treatment of astigmatism. The Melbourne multizone technique equally divided myopia correction into a maximum of three ablation zones. The Pop multizone technique biased myopia treatment into the smaller diameter zones to a maximum of six ablation zones, with one central island pretreatment. The Alpins multizone technique equally divided myopia treatment through all zones up to a maximum of six, with one central island pretreatment. RESULTS A total of 585 patients (780 eyes) were treated and 625 eyes (80%) were followed for more than 6 months. The mean baseline spherical equivalent refractive error was -5.63 D (-1.00 to -19.50 D). Between 71 and 79% of eyes were treated for astigmatism. There was no statistically significant differences in baseline refractive error or other characteristics among the three groups. At 6 months, the Alpins multizone algorithm had more eyes with a refractive error within +/- 1.00 D of emmetropia (p = 0.01) and more within +/- 2.00 D of emmetropia (p < 0.01). This new algorithm produced more eyes with an uncorrected visual acuity of 20/20 or better at 6 months (p < 0.01). When multiple logistic regression was used to correct for any differences in baseline myopia among the three groups, this algorithm also had a higher odds ratio for achieving 20/20 or better uncorrected visual acuity (OR = 1.58). CONCLUSION At 6 months, all three algorithms were effective in the reduction of myopia. Significantly better visual acuity and refractive results were achieved with the Alpins multizone algorithm that spread the total treatment over a larger number of ablation zones, with an equal number of diopters of treatment in each zone.

Excimer laser correction of astigmatism with multipass/multizone treatment

Purpose: To evaluate the accuracy of excimer laser correction of myopic astigmatism by multipass/multizone photoastigmatic refractive keratectomy (PARK). Setting: Tertiary referral ophthalmic hospital with an associated private laser facility. Methods: This study comprised a consecutive series of 332 eyes of 289 patients who were followed for 6 months. All patients were 18 years or older, had stable myopic astigmatism (up to a −19.0 diopters [D] spherical equivalent [SE] at the spectacle plane), and had a best corrected visual acuity of at least 20/60 in both eyes. All eyes were treated with a VISX Twenty‐Twenty excimer laser. The correction was divided between ablation zones using a multipass/multizone treatment paradigm based on the amount of myopia and astigmatism. Patients were examined 1 week, and 1, 3, and 6 months after surgery. Results: Analysis of the mean percentage of spherical correction across the range of myopic preoperative SEs treated demonstrated 90% correction for most amounts of myopic astigmatism. Eyes with low myopia (mean preoperative SE ≤ −5.0 D) treated with ≤ −1.0 diopter cylinder (DC) of astigmatism achieved a mean percentage of spherical correction of 91% versus 93% in eyes with high myopia (>−5.0 D mean preoperative SE). Eyes with low myopia treated with >−1.0 DC of astigmatism achieved a mean percentage spherical correction of 90% versus 89% in eyes with high myopia. The differences between the two groups were not statistically significant. Patients with high relative cylinder (>80% of total sphere treated) achieved comparable results. Analysis of the astigmatic component of the treatment, independent of the spherical result, showed a trend toward overcorrection in the high myopia group with less than −1.0 DC and a mean astigmatic correction of 89 and 98%, respectively, in the low and high myopic astigmatism groups. The mean angle of error was +2.0 degrees. Conclusion: Multipass/multizone PARK for myopic astigmatism demonstrated a high degree of predictability and stability with desirable results for low and high levels of astigmatism across the range of myopic astigmatism treated by surface ablation.

Role of Genetic Factors in Lower- and Higher-Order Aberrations – The Genes in Myopia Twin Study

Aims: We intended to investigate the relative genetic contribution in wavefront aberrations using a sub-group of twins recruited in the Genes in Myopia twin study, and subsequently provide direction for future studies into the aetiology of mono-chromatic aberrations. To our knowledge, the Genes in Myopia twin study is the first study to explore the role of genetic factors in both lower- and higher-order aberrations in a Caucasian population. Methods: Each individual completed a general questionnaire and underwent a comprehensive eye examination. Higher-order wavefront aberrations were calculated with Zernike coefficients up to the fourth order. Results: A total of 46 twin pairs with a mean age of 65.3 years were included in the analysis. Monozygotic intra-pair correlations were significantly higher compared to those in dizygotic twin pairs for defocus aberrations (p < 0.05). A trend for a genetic component was identified for higher-order aberrations. Conclusion: Genetic studies into refraction typically explore the genetic effects of lower-order aberrations such as myopia and hypermetropia; however, there is little to no research into the genetic basis of higher-order aberrations. The Genes in Myopia twin study indicates a potential genetic role for higher-order aberrations and provides useful insights into the aetiology of refractive error.