Cylindrical Refractive Error Research Articles

Prevalence of Myopia, Hyperopia, and Astigmatism in Non-Hispanic White and Asian Children: Multi-Ethnic Pediatric Eye Disease Study

To determine the age-, gender-, and ethnicity-specific prevalence of myopia, hyperopia, and astigmatism in non-Hispanic white (NHW) and Asian preschool children. Population-based, cross-sectional study. A population-based sample of 1501 NHW children and 1507 Asian children aged 6-72 months from Los Angeles County and Riverside County, California. Eligible children underwent an in-home and in-clinic interview and a comprehensive eye examination including cycloplegic autorefraction from 100 census tracts. The proportion of children with myopia (spherical equivalent [SE] ≤-1.00 diopter [D]), hyperopia (SE ≥ +2.00 D) and cylindrical refractive error ≥1.50 D in the worse eye. The astigmatism type was defined as with-the-rule (WTR; +cylinder axis 90°±15°) and against-the-rule (ATR; + cylinder axis 180°±15°); all other orientations were considered oblique (OBL). The prevalence of myopia, hyperopia, and astigmatism in NHW children was 1.20% (95% confidence interval [CI], 0.76%-1.89%), 25.65% (95% CI, 23.5%-27.9%), and 6.33% (95% CI, 5.21%-7.68%), respectively. The prevalence of WTR, ATR, and OBL astigmatism in NHW children was 4.33%, 1.00%, and 1.00%, respectively. Prevalence was lower with older age groups for astigmatism (P = 0.0002), but not for myopia (P = 0.82) or hyperopia (P = 0.31). In Asian children, the prevalence of myopia, hyperopia, and astigmatism was 3.98% (95% CI, 3.11%-5.09%), 13.47% (95% CI, 11.8%-15.3%), and 8.29% (95% CI, 7.01%-9.80%), respectively. The prevalence of WTR, ATR, and OBL astigmatism was 6.50%, 0.80%, and 1.00% respectively. The prevalence of hyperopia was higher in girls than boys (P = 0.0002), but no differences were found for myopia and astigmatism. Hyperopia was the most common refractive error in both Asian and NHW children. However, compared with NHW children, myopia was relatively more prevalent, and hyperopia less prevalent, among Asian children. The prevalence of astigmatism was greatest in infants, and WTR astigmatism predominated at all ages. Myopia showed relatively stable prevalence across age groups, whereas hyperopia prevalence decreased after infancy and then increased again in older age groups; however, longitudinal studies are needed to evaluate refractive changes over time in individual children. The authors have no proprietary or commercial interest in any of the materials discussed in this article.

Myopic Maculopathy Imaged by Optical Coherence Tomography: The Beijing Eye Study

To examine the features of myopia-related optical coherence tomography (OCT) findings in a population-based setting. Population-based study. The Beijing Eye Study 2011 included 3468 subjects with an age of 50 years or more. The participants underwent a detailed ophthalmic examination including OCT with enhanced depth imaging of the macula. Optical coherence tomography features of the macula in highly myopic eyes defined by a refractive error of-6 diopters or less or an axial length of 26.5 mm or more. Readable OCT images were available for 6530 eyes (94.5%) of 3278 participants. The most common change in the macula was maculoschisis (0.8±0.1%), followed by incomplete posterior vitreous detachment (0.7±0.1%), disruption of the photoreceptor inner segment/outer segment interface (0.6±0.1%), epiretinal membranes (0.6±0.1%), macular defects in Bruch's membrane (0.3±0.1%), clumping of the retinal pigment epithelium (0.2±0.1%), vitreofoveal adhesion (0.2±0.1%), and macular holes in 2 eyes (0.1±0.1%). Prevalence of any myopic maculopathy per eye was 112 of 6530, or 1.71±0.16% (95% confidence interval [CI], 1.40-2.03). After adjustment for longer axial length (P<0.001; odds ratio [OR], 2.68; 95% CI, 1.97-3.64) and myopic refractive error (P<0.001; OR, 0.63; 95% CI, 0.55-0.73), presence of any myopic maculopathy was not significantly associated with any systemic variables (all P≥0.05), including biochemical blood examination and ocular parameters. Best-corrected visual acuity was associated significantly with the absence of a disruption of the photoreceptor inner segment/outer segment interface (P<0.001), epiretinal membranes (P<0.001), and macular holes (P<0.001) after adjustment for age and cylindrical refractive error. Based on OCT examination, the most common macular change in highly myopic eyes was maculoschisis, followed by incomplete posterior vitreous detachment, disruption of the photoreceptor inner segment/outer segment interface, epiretinal membranes, macular defects in Bruch's membrane, clumping of the retinal pigment epithelium, vitreofoveal adhesion, and macular holes. The most important macular changes with a negative effect on best-corrected visual acuity were a disruption of the photoreceptor inner segment/outer segment interface and epiretinal membranes.

Clinical Results of Topography-based Customized Ablations for Myopia and Myopic Astigmatism

To evaluate clinical outcomes after primary treatments for myopia and myopic astigmatism with topography-based ablation profiles on the Allegretto Wave Eye-Q platform (Alcon Laboratories Inc). Records of patients who underwent topography-guided, Q-adjusted LASIK were retrieved and analyzed. Patients with mean refractive spherical equivalent up to -16.00 diopters (D) and cylindrical errors up to 6.00 D were included (2051 eyes). Refractive outcomes and visual acuities were analyzed preoperatively and 3 months postoperatively. Manifest spherical refractive error decreased from -5.05 +/- 2.33 to +0.04 +/- 0.35 D. Manifest cylindrical refractive error decreased from 0.83 +/- 0.75 to 0.23 +/- 0.22 D. At 3 months postoperatively, 86.1% (1766 eyes) had a spherical equivalent refraction within +/- 0.50 D of targeted refraction. The number of eyes with uncorrected distance visual acuity of 20/16 and 20/20 was 851 (41.5%) and 1495 (72.9%), respectively. At 3 months, 0.10% (2 eyes) lost more than 2 lines of corrected distance visual acuity and a loss of 2 lines occurred in 0.24% (5 eyes). All patients who lost lines of visual acuity were found to have corneal erosions related to dryness and recovered vision on further follow-up. The results of this retrospective study demonstrate refractive predictability, efficacy, and safety comparable to other treatment modalities such as wavefront-optimized and wavefront-guided treatments. Results are also similar to those reported with other topography-guided systems.

Visual and Refractive Outcome of Epi-LASIK for Myopia in Thin Corneas: a 12-Month Follow-Up

A nonrandomized, retrospective, cohort, single-center study was designed to examine the visual and refractive outcome of epi-laser-assisted in situ keratomileusis (LASIK) for myopia (with and without astigmatism) in patients with thin corneas (less than 500 µm), and to compare these results with those of a group of patients with normal corneal thickness. Uncorrected distance visual acuity (UCVA), spherical and cylindrical residual refractive error, mean keratometry readings (Km), and pupil diameter were measured postoperatively at 24 hours, 1 week, 1 month, 3 months, and 12 months in a group of 28 eyes with thin corneas (group 1) and a second age- and gender-matched group of 28 eyes with normal corneal thickness (group 2). In addition, the efficacy index was calculated at every postoperative examination. Postoperative central corneal thickness was 464.14±50.40 µm in group 1 and 421.89±26.63 µm in group 2 (p<0.001). No statistically significant difference was found in UCVA, efficacy index, and spherical and cylindrical residual error between both groups, with an evolution towards stability over time in all cases. Statistically significant between-group differences in Km at all follow-up examinations were explained by between-group differences in ablation depth and attempted spherical correction. A 12-month follow-up revealed epi-LASIK for myopia (with and without astigmatism) to be a safe and predictable surface ablation procedure, with good visual and refractive outcome in patients with thin corneas, as compared with a group of patients with normal corneal thickness.

Prevalence and associations of steep cornea/keratoconus in Greater Beijing. The Beijing Eye Study.

PurposeTo evaluate the prevalence and associated factors of steep cornea/keratoconus in the adult Chinese population.MethodsThe population-based Beijing Eye Study 2011 included 3468 individuals with a mean age of 64.6±9.8 years (range: 50–93 years). A detailed ophthalmic examination was performed including optical low-coherence reflectometry. Steep cornea/keratoconus were defined as an anterior corneal refractive power exceeding 48 diopters.ResultsMean refractive power of the cornea was 43.16±1.45 diopters (range: 36.51 to 48.46 diopters; flattest meridian) and 43.98±1.52 diopters (range: 37.00 to 52.88 diopters; steepest meridian). A steep cornea/keratoconus defined as corneal refractive power of ≥48 diopters and ≥49 diopters was detected in 27 subjects (prevalence rate: 0.9±0.2%) and 6 (0.2± 0.1%) subjects, respectively. Presence of steep cornea/keratoconus was associated with shorter axial length (P<0.001), smaller interpupillary distance (P = 0.038), lower best corrected visual acuity (P = 0.021), higher cylindrical refractive error (P<0.001) and more myopic refractive error (P<0.001). It was not significantly associated with gender, body height, psychic depression, cognitive function, blood concentrations of glucose, lipids, creatinine and C-reactive protein, blood pressure and quality of life score, nor with intraocular pressure, dry eye feeling, and lens thickness.ConclusionsA steep cornea/keratoconus defined as corneal refractive power of 48+ diopters has a prevalence of 0.9±0.2% among Chinese aged 50 years and above. Its prevalence was significantly associated with the ocular parameters of shorter axial length, smaller interpupillary distance, higher cylindrical and myopic refractive error and lower best corrected visual acuity, however, with none of the systemic parameters tested.

KeraRing Intrastromal Corneal Ring Segments for Correction of Keratoconus

Intrastromal corneal ring segments (ICRSs) are small arc-like implants that are being used increasingly as a minimally invasive treatment for patients with keratoconus. This study assessed the effectiveness of KeraRing implants, a type of ICRS, to treat keratoconus. Retrospective case series descriptive study of 43 patients (55 eyes) with keratoconus who underwent KeraRing implantation from February 2008 to June 2009. Patients who had intraoperative or postoperative complications and/or did not complete at least 6 months of follow-up were excluded. All patients underwent complete ophthalmologic examinations that included measurement of the uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, and keratometry before and 2 days, 2 weeks, 1 month, and 3 and 6 months after surgery. The ring segments were chosen based on a nomogram from the manufacturer. Six months postoperatively, the mean UCVA increased significantly (P < 0.05) from 0.10 ± 0.11 to 0.32 ± 0.25 and the mean BSCVA increased from 0.36 ± 0.23 to 0.57 ± 0.24 (P < 0.05). The mean spherical refractive error significantly (P < 0.05) improved from -4.85 ± 2.90 diopters (D) to -1.89 ± 2.68 D, and the mean cylindrical refractive error significantly (P < 0.05) improved from -3.65 ± 1.70 D to -2.60 ± 1.62 D. The mean spherical equivalent significantly (P < 0.05) decreased from -6.68 ± 2.93 D to -3.19 ± 2.75 D, and the mean keratometry value decreased from 51.83 ± 4.14 D to 47.27 ± 3.68 D. The improvement in the UCVA and BSCVA continued over the 6-month postoperative period, but significant changes occurred only during the first 3 months. These changes occurred in patients with all grades of keratoconus. KeraRing implantation provided significant improvement in visual acuity, spherical equivalent, and keratometry results. This ICRS is an effective treatment for managing keratoconus and might delay or even avoid the need for penetrating keratoplasty.

Impairment of contrast visual acuity as a functional correlate of retinal nerve fibre layer thinning and total macular volume reduction in multiple sclerosis

ObjectivesTo analyse the association between retinal nerve fibre layer thickness (RNFLT) and total macular volume (TMV) as measured by optical coherence tomography, and contrast sensitivity (CS) measured by Functional Acuity...

The Child Self-Refraction Study: Results from Urban Chinese Children in Guangzhou

To compare visual and refractive outcomes between self-refracting spectacles (Adaptive Eyecare, Ltd, Oxford, UK), noncycloplegic autorefraction, and cycloplegic subjective refraction. Cross-sectional study. Chinese school-children aged 12 to 17 years. Children with uncorrected visual acuity ≤ 6/12 in either eye underwent measurement of the logarithm of the minimum angle of resolution visual acuity, habitual correction, self-refraction without cycloplegia, autorefraction with and without cycloplegia, and subjective refraction with cycloplegia. Proportion of children achieving corrected visual acuity ≥ 6/7.5 with each modality; difference in spherical equivalent refractive error between each of the modalities and cycloplegic subjective refractive error. Among 556 eligible children of consenting parents, 554 (99.6%) completed self-refraction (mean age, 13.8 years; 59.7% girls; 54.0% currently wearing glasses). The proportion of children with visual acuity ≥ 6/7.5 in the better eye with habitual correction, self-refraction, noncycloplegic autorefraction, and cycloplegic subjective refraction were 34.8%, 92.4%, 99.5% and 99.8%, respectively (self-refraction versus cycloplegic subjective refraction, P<0.001). The mean difference between cycloplegic subjective refraction and noncycloplegic autorefraction (which was more myopic) was significant (-0.328 diopter [D]; Wilcoxon signed-rank test P<0.001), whereas cycloplegic subjective refraction and self-refraction did not differ significantly (-0.009 D; Wilcoxon signed-rank test P = 0.33). Spherical equivalent differed by ≥ 1.0 D in either direction from cycloplegic subjective refraction more frequently among right eyes for self-refraction (11.2%) than noncycloplegic autorefraction (6.0%; P = 0.002). Self-refraction power that differed by ≥ 1.0 D from cycloplegic subjective refractive error (11.2%) was significantly associated with presenting without spectacles (P = 0.011) and with greater absolute power of both spherical (P = 0.025) and cylindrical (P = 0.022) refractive error. Self-refraction seems to be less prone to accommodative inaccuracy than noncycloplegic autorefraction, another modality appropriate for use in areas where access to eye care providers is limited. Visual results seem to be comparable. Greater cylindrical power is associated with less accurate results; the adjustable glasses used in this study cannot correct astigmatism. Further studies of the practical applications of this modality are warranted. Proprietary or commercial disclosure may be found after the references.

Real and Pseudoaccommodation in Accommodative Lenses

In the attempt to manage presbyopia, different intraocular lens designs have been proposed such as monofocal IOLs with monovision or multifocal IOLs. Even though the lenses mentioned offer satisfactory visual results, contemporary ophthalmology has not completely answered the presbyopic dilemma by simulating the accommodative properties of the crystalline lens itself. Accommodative IOLs were designed to fill this gap and provide satisfactory vision for all distances by restoring some degree of “pseudoaccommodation.” Pseudo accommodative capability can be linked to monofocal IOL's as well but the results are not satisfactory enough to fully support unaided near vision. Pseudoaccommodation is a complex phenomenon that can be attributed to several static (i.e., pupil size, against-the-rule cylindrical refractive error, multifocality of the cornea) and dynamic (i.e., anterior movement of the implant itself) factors. Objective measurement of the accommodative capability offered by the accommodative IOLs is extremely difficult to obtain, and different methods such as autorefractometers, retinoscopy, and ultrasound imaging during accommodative effort, ray tracing, or pharmacological stimulation have been developed but the results are sometimes inconsistent. Despite the difficulties in measuring accommodation, accommodative IOLs represent the future in the attempt to successfully “cure” presbyopia.

Evaluation of intrastromal corneal ring segments for treatment of post-LASIK ectasia patients with a mechanical implantation technique

Aim:To evaluate the clinical outcomes of Keraring segment implantation in patients with post- laser-assisted in situ keratomileusis (LASIK) ectasia, using a mechanical implantation technique.Materials and Methods:Twelve eyes of 10 patients with post-LASIK ectasia were enrolled. Intracorneal ring segments (ICRS) were implanted after dissection of the tunnel using Tunc's specially designed dissector under suction. A complete ophthalmic examination was performed, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), spherical equivalent, keratometric (K) readings, inferosuperior asymmetry index (ISAI), and ultrasound pachymetry. All 3, 6, and 12-month follow-ups were completed, and statistical analysis was performed.Results:The mean preoperative UDVA for all eyes was 1.28 ± 0.59 logMAR. At 12 months, the mean UDVA was 0.36 ± 0.19 logarithm of the Minimum Angle of Resolution (logMAR) (P=0.002), and the mean preoperative CDVA was 0.58 ± 0.3 logMAR, which improved to 0.15 ± 0.12 (P=0.002) at 1 year. There was a significant reduction in cylindrical refractive and spherical equivalent refractive error from –5.29 ± 2.47 diopters (D) and –5.54 ± 5.04 D preoperatively to –1.47 ± 0.71 D and –0.74 ± 1.07 D (P=0.001, P=0.002), respectively, at 1 year. In the same period, the mean K- readings improved from 47.93 ± 4.84 D to 40.87 ± 2.36 D (P=0.002), and the mean ISAI improved from 5.34 ± 3.05 to 2.37 ± 1.68 (P=0.003). No significant changes in mean central corneal thickness were observed postoperatively. There were no major complications during or after surgery.Conclusion:ICRS implantation using a unique mechanical dissection technique is a safe and effective treatment for post-LASIK ectasia. All parameters showed improvement at 1-year follow-up.

Evolution of postoperative astigmatism after large incision PMMA lens implantation in children

To investigate the evolution of postoperative astigmatism after cataract extraction and lens implantation in children through a 6.5 mm limbal incision. This is a retrospective longitudinal study of consecutive pediatric patients with adequate follow-up who underwent cataract extraction with intraocular lens implantation through a 6.5 mm limbal incision. Preoperative and 3-month postoperative astigmatism and spherical equivalent were compared. A total of 92 eyes of 73 children met the inclusion criteria. The mean cylindrical correction on the first postoperative day was 6.6 ± 2.3 D (range, 1.00-13.00 D). This dropped to 1.9 ± 1.7 D between 2 and 4 weeks and 1.2 ± 1.0 D (range, 0-3.25 D) by 3 months postoperatively. The mean spherical equivalent was +0.5 D on the first postoperative day and did not change significantly during the follow-up period. The mean astigmatism preoperatively (1.2 ± 0.8 D) and 3 months postoperatively (1.2 ± 1.0 D) were not statistically different (p = 0.9). There was no statistically significant change in astigmatism between 1 and 3 months and 1 and 2 years (p = 0.16, n = 33). Large cylindrical refractive errors after pediatric cataract surgery through a 6.5 mm limbal incision resolve postoperatively within 3 months.

Prevalence of Astigmatism in 6- to 72-Month-Old African American and Hispanic Children: The Multi-Ethnic Pediatric Eye Disease Study

To determine the age-, gender-, and ethnicity-specific prevalence of astigmatism in African American and Hispanic children aged 6 to 72 months. Population-based, cross-sectional study. The Multi-Ethnic Pediatric Eye Disease Study is a population-based evaluation of the prevalence of vision disorders in children ages 6 to 72 months in Los Angeles County, California. Seventy-seven percent of eligible children completed a comprehensive eye examination. This report provides the results from 2994 African American and 3030 Hispanic children. Eligible children in 44 census tracts were identified during an in-home interview and scheduled for a comprehensive eye examination and in-clinic interview. Cycloplegic autorefraction was used to determine refractive error. The proportion of children with astigmatism defined as cylindrical refractive error ≥ 1.50 diopters (D) in the worse eye. The astigmatism type was defined as with-the-rule (WTR) (+ cylinder axis 90 ± 15 degrees) and against-the-rule (ATR) (+ cylinder axis 180 ± 15 degrees); all other orientations were considered oblique (OBL). The prevalence of astigmatism and its types were also determined for worse eye cylindrical refractive error ≥ 3.00 D. Prevalence of astigmatism ≥ 1.50 D was higher in Hispanic children compared with African American children (16.8% vs. 12.7%, respectively; P<0.0001). Hispanic children also showed a higher prevalence of astigmatism ≥ 3.00 D than African American children (2.9% vs. 1.0% respectively; P<0.0001). The prevalence of astigmatism ≥ 1.50 D showed a significant decreasing trend with age (P<0.0001). The prevalence of WTR, ATR, and OBL astigmatism ≥ 1.50 D was 13.9%, 0.6%, and 2.2%, respectively, in Hispanic children, and 7.8%, 2.2%, and 2.7%, respectively, in African American children. We observed ethnicity-related differences in astigmatism prevalence in preschool children. The age-related decrease in astigmatism prevalence in preschool children likely reflects emmetropization.

Intracorneal continuous ring implantation for keratoconus: One-year follow-up

To evaluate intracorneal continuous ring (ICCR) implantation for the treatment of keratoconus. Eye specialist centers, Europe and Middle East. This study assessed the results of implantation of a MyoRing ICCR in 15 eyes with keratoconus. Outcome measures included uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA) (spectacle correction), refraction, complications, and side effects. Postoperative follow-up was up to 1 year. The study evaluated 15 eyes of 11 patients (8 men, 3 women) with a mean age of 35 years +/- 12 (SD) (range 22 to 60 years). Preoperatively, the mean central corneal thickness was 435 +/- 41 mum (range from 350 to 485 mum) and the mean keratometry (K) readings, 48.96 +/- 3.4 diopters (D) (range 43.75 to 56.62 D). Postoperatively, there was a statistically significant improvement in the UDVA, CDVA, K readings, manifest spherical and cylindrical refractive errors, and spherical equivalent (P<.05). The mean UDVA improved by almost 10 lines, from 0.07 (1.24 +/- 0.35 logMAR) to 0.56 (0.27 +/- 0.17 logMAR), and the mean CDVA improved by almost 3 lines, from 0.42 (0.40 +/- 0.17 logMAR) to 0.77 (0.12 +/- 0.10 logMAR). The mean K reading decreased by 5.76 D, from 48.96 D to 43.20 D. No serious intraoperative complications occurred. Side effects included glare and night-vision problems. Treatment of keratoconus with ICCR implantation significantly improved visual function. The nomogram requires grading the disease using the K readings only. The UDVA and CDVA also improved during the first postoperative year. Drs. Mahmoud and Venkateswaran have no financial or proprietary interest in any material or method mentioned. Additional disclosure is found in the footnotes.

Effect of intraoperative aberrometry on the rate of postoperative enhancement: Retrospective study

To determine whether the use of intraoperative wavefront aberrometry reduces the frequency of postoperative laser enhancements over the rate in cases in which aberrometry was not used. Private surgical center and private practice, Eugene, Oregon, USA. This was a retrospective case-control chart review of patients who chose to have correction of preexisting corneal astigmatism by limbal relaxing incisions (LRIs) at the time of cataract surgery or refractive lens exchange. In the aberrometry group, an ORange wavefront aberrometer was used intraoperatively to measure total ocular refractive cylinder after intraocular lens implantation and to guide LRI enhancement. A group in which the aberrometer was not used served as the control. The control group had 37 eyes and the aberrometry group, 30 eyes. The excimer laser enhancement rate was 3.3% in the aberrometry group and 16.2% in the control group. The mean postoperative cylinder was 0.48 diopter (D) in the control group and 0.37 D in the aberrometry group. Residual cylindrical refractive error, not sphere, determined the patients' decision to have enhancement. The use of intraoperative wavefront aberrometry to measure and enhance the effect of LRIs produced a nonsignificant trend that led to a 5.7-fold reduction in the odds ratio of subsequent excimer laser enhancement.

Topography-Guided vs Wavefront-Optimized Surface Ablation for Myopia Using the WaveLight Platform: A Contralateral Eye Study

to compare treatments with wavefront-optimized and topography-guided ablations. this prospective, randomized, contralateral study comprised 40 eyes (20 patients) with low to moderate myopia with or without astigmatism that underwent topography-guided photorefractive keratectomy (PRK) (ALLEGRO Topolyzer, Alcon Laboratories Inc) in one eye and wavefront-optimized PRK (ALLEGRETTO WAVE software version 2.020 default treatment, Alcon Laboratories Inc) in the fellow eye. Visual acuity, refractive error, contrast sensitivity, and Orbscan (Bausch & Lomb) 3- and 5-mm corneal irregularities were measured preoperatively and 3 and 6 months postoperatively. The results were compared between the two eyes. in both groups, preoperative corrected distance visual acuity (CDVA) (0.03±0.09 logMAR for topography-guided and 0.01 ± 0.06 logMAR for wavefront-optimized [P=.1]), 3-month postoperative uncorrected distance visual acuity (UDVA) (-0.0 1± 0.03 logMAR for topography-guided and -0.01 ± 0.03 logMAR for wavefront-optimized [P=.4]), and 6-month postoperative UDVA (0.01 ± 0.03 logMAR for topography-guided and 0.0 ± 0.01 logMAR for wavefront-optimized [P=.3]) were the same. All wavefront-optimized and 18 (90%) topography-guided eyes had UDVA of 20/20 or better. No significant differences were noted between groups in pre- and postoperative spherical and cylindrical refractive errors or corneal irregularity and contrast sensitivity measurements. Six months postoperatively, contrast sensitivity values at 3, 6, 12, and 18 cycles/degree were 5.7 ± 0.7, 6.0 ± 1.5, 6.1 ± 1.3, and 5.5 ± 1.5, respectively, in the topography-guided group, and 6.2 ± 0.6, 6.4 ±1.2, 6.4 ± 1.1, and 5.8 ± 1.3, respectively, in the wavefront-optimized group (P=.3, P=.5, P=.4, and P=.6, respectively). using the WaveLight excimer laser platform for PRK, CDVA and contrast sensitivity outcomes were statistically similar between the wavefront-optimized and topography-guided ablations in eyes with low to moderate myopia with and without astigmatism.

Femtosecond Laser-Assisted Mushroom Configuration Deep Anterior Lamellar Keratoplasty

To review patient outcomes after femtosecond laser-assisted mushroom configuration deep anterior lamellar keratoplasty. Seven eyes of seven patients with a mean age of 30 years underwent femtosecond laser-assisted mushroom configuration deep anterior lamellar keratoplasty from April 2008 to September 2008. Patients had keratoconus, corneal ectasia or scarring. Set for 100 mum of residual cornea, the femtosecond laser was used to create a mushroom-shaped recipient bed and donor button (having a larger anterior than posterior diameter). The posterior central lamella was manually dissected using Melles technique. Mean follow up was 4 months (range, 3-6.5 months). Preoperative mean best-corrected visual acuity was 20/95 (range, 20/40-20/400). Intraoperative complications included two cases (28.6%) of small Descemet membrane perforation. Postoperatively, there was one case of stromal rejection that resolved with topical steroids and two cases of steroid-related intraocular pressure rise that were treated with a prostaglandin analog. At 3 months, mean best-corrected visual acuity was 20/40 (range, 20/25-20/60), mean spherical equivalent refraction was -3.21 D (range, -6.75 D to plano), mean cylindrical refractive error was 3.57 D (range, 1.5-7 D), and mean keratometric cylinder measured 5.56 D (range, 3.79-7.00 D). Selective suture removal occurred in six patients (86%) at a mean of 3.8 months (range, 2-6 months) postoperatively. This preliminary series demonstrates that the use of the femtosecond laser to perform corneal cuts in a mushroom configuration for deep anterior lamellar keratoplasty is feasible. The mechanical stability and wound healing advantages for stepped corneal wounds should be considered in lamellar surgery.

Implantation of a Complete Corneal Ring in an Intrastromal Pocket for Keratoconus

to evaluate the refractive and visual results of a new treatment for keratoconus using the corneal intrastromal implantation system (CISIS). six eyes of four patients with keratoconus were treated with CISIS. Follow-up was 1, 3, and 6 months. After creating an intracorneal pocket of 9-mm diameter and 300-microm depth, a flexible full-ring implant was inserted via a 4-mm-wide corneal tunnel. no eyes showed loss of lines in uncorrected distance visual acuity (UDVA) or spectacle corrected distance visual acuity (CDVA) at any follow-up examination. Uncorrected and distance corrected visual acuity, keratometry, spherical and cylindrical refractive error as well as spherical equivalent refraction improved significantly (P<.05). Mean UDVA improved from 20/260 to 20/48 and mean CDVA improved from 20/41 to 20/27. A significant centralization and decrease of the corneal apex was found. No intra- or postoperative complications were observed. the corneal intrastromal implantation system using a complete ring implanted in a stromal pocket can achieve significant improvements in the visual function of patients with keratoconus. Uncorrected distance visual acuity improved by more than seven lines on average and CDVA improved by two lines.

Refractive Error May Influence Mesopic Pupil Size

Purpose: To identify factors which affect mesopic pupil diameter in refractive surgery patients.Setting: This retrospective study was performed at the 1st Ophthalmology Clinic in Ankara Ataturk Training and Research Hospital, Ankara, Turkey.Methods: Medical records of 412 refractive surgery candidates who applied between 2006 and 2008 were reviewed. Detailed ophthalmological examination data were obtained from medical records. Pupil size measurements were performed with a COAS Ocular Wavefront analyzer in mesopic conditions. Relationship between mesopic pupil diameter and age, sex, spherical refractive error (D), magnitude of astigmatism (D), type of astigmatism, spherical equivalent, and average keratometry were analyzed by means of univariate and multivariate regression analyses.Results: Mean mesopic pupil diameter was 6.19 ± 0.88 mm. Mean pupil diameter (mean ± standard deviation) was 5.70 ± 1.01 in hypermetropia, 6.04 ± 0.79 mm in mixed astigmatism, and 6.33 ± 0.82 mm in myopia. The difference in mean mesopic pupil diameters between myopes and hypermetropes was statistically significant (p = 0.001). However, differences with regard to mean pupil diameters between myopes and mixed astigmatism (p = 0.660) and between hypermetropes and mixed astigmatism (p = 0.109) were not significant. Mean pupil diameter was 6.00 ± 0.99 mm in against the rule astigmatism, 5.96 ± 0.84 mm in oblique astigmatism, and 6.27 ± 0.84 mm in with the rule astigmatism. Mean mesopic pupil diameter in with the rule astigmatism group was higher than oblique astigmatism group. Spherical refractive error (r = -0.213, p = 0.001), cylindrical refractive error (0.197, p = 0.001), and age (r = −0.341, p = 0.001) showed correlation with pupil diameter.Conclusions: This study showed that age and magnitude of both spherical and cylindrical refractive error are the most determinative factors on mesopic pupil size.

Central Corneal Thickness and Its Association with Ocular and General Parameters in Indians: The Central India Eye and Medical Study

To evaluate the distribution of central corneal thickness (CCT) and its associations in an adult Indian population. Population-based study. The Central India Eye and Medical Study is a population-based study performed in a rural region close to Nagpur in Central India; it included 4711 subjects (ages 30+ years) of 5885 eligible subjects (response rate, 80.1%). The participants underwent a detailed ophthalmic and medical examination, including 200 standardized questions on socioeconomic background, lifestyle, social relations, and psychiatric depression. This study was focused on CCT as measured by sonography and its associations. Intraocular pressure was measured by applanation tonometry. Central corneal thickness and intraocular pressure. Central corneal thickness measurement data were available on 9370 (99.4%) eyes. Mean CCT was 514+/-33 microm (median, 517 microm; range, 290-696 microm). By multiple regression analysis, CCT was associated significantly with younger age (P<0.001), male gender (P<0.001), higher body mass index (P = 0.006), lower corneal refractive power (P<0.001), deeper anterior chamber (P = 0.02), thicker lens (P = 0.02), and shorter axial length (P = 0.006). Central corneal thickness was not associated significantly with refractive error (P = 0.54) or cylindrical refractive error (P = 0.20). If eyes with a corneal refractive power of 45 or more diopters were excluded, the relationship between CCT and axial length was no longer statistically significant (P>0.05), whereas all other relationships remained significant. Intraocular pressure readings increased significantly (P<0.001) with both higher CCT and higher corneal refractive power. Indians from rural Central India have markedly thinner corneas than do Caucasians or Chinese, and, as in other populations, CCT is greater in men. CCT was associated with younger age, higher body mass index, lower corneal refractive power, deeper anterior chamber, thicker lens, and shorter axial length. Intraocular pressure readings were associated with CCT, with high readings in those eyes that had thick corneas or steep corneas. Central corneal thickness and steepness of the anterior corneal surface may thus both have to be taken into account when applanation tonometry is performed. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

The Influence of Factors Before Wearing Reverse-Geometry Lens on Visual Acuity After Wearing Reverse-Geometry Lens

Purpose: To determine whether patient factors (pre-fitting patient's data) before reverse-geometry lens (RGL) use could be predicting factors for the increase in visual acuity after RGL use. Methods: The authors reviewed out patient records of 805 eyes of 423 patients wearing RGLs from March 2003 to May 2009. The relationship between patient factors on UVA before wearing a RGL examined at follow-ups and the IVA after wearing a RGL were analyzed. Results: The spherical refractive errors and the cylindrical refractive errors showed statistically significant results (p 0.05). Conclusions: The refractive error and the corneal astigmatism may be strong predictors of UVA and IVA after RGL use.