Category: Peer-reviewed

Corneal Topographic and Tomographic Analysis of Fellow Eyes in Unilateral Keratoconus Patients Using Pentacam – Corrected Proof

by  •  • 0 Comments

Purpose: To evaluate topographic and tomographic changes in fellow eyes in unilateral keratoconus (KCN) patients by comparing them with normal eyes.Design: Retrospective comparative case series.Methods: Fourteen eyes of 14 patients with unilateral KCN and 34 eyes of 34 refractive surgery candidates were divided into 3 diagnostic groups using a Pentacam rotating Scheimpflug camera: advanced KCN eyes of unilateral KCN (KCN group, 14 eyes), normal fellow eyes of unilateral KCN (fellow eye group, 14 eyes), and refractive surgery candidates (normal group, 34 eyes). Topographic and tomographic parameters, which were obtained from Pentacam using sagittal curvature, elevation, and corneal thickness maps, were compared among the 3 groups. Receiver operating characteristic (ROC) curves were used to identify cutoff points in discriminating between fellow and normal eyes.Results: Keratometric asymmetry, topometric indices, and elevation differences (maximum − minimum) on both the anterior and posterior surfaces were statistically different (P < .05). On ROC curve analysis, keratometric asymmetry and topometric index were best at discriminating fellow eyes from normal, followed by elevation differences (maximum − minimum) on the posterior and anterior cornea surface.Conclusions: Fellow eyes in unilateral KCN showed differences in several parameters that were not detectable with the Pentacam detection program, when compared with normal. However, each single parameter alone is not sufficient to detect early changes; thus, elevation indices as well as indices of anterior curvature should be considered together.

Read more →

Long-Term Trends in Glaucoma-Related Blindness in Olmsted County, Minnesota – Corrected Proof

by  •  • 0 Comments

Objective: To determine the longitudinal trends in the probability of blindness due to open-angle glaucoma (OAG) in Olmsted County, Minnesota, from 1965 to 2009.Design: Retrospective, population-based cohort study.Participants: All residents of Olmsted County, Minnesota (aged ≥40 years) who were diagnosed with OAG between January 1, 1965, and December 31, 2000.Methods: All available medical records of every incident case of OAG were reviewed until December 31, 2009, to identify progression to blindness, defined as visual acuity ≤20/200 or visual field constriction to ≤20°. Kaplan–Meier analysis was used to estimate the cumulative probability of glaucoma-related blindness. Population incidence of blindness within 10 years of diagnosis was calculated using US Census data. Rates for subjects diagnosed in the period 1965–1980 were compared with rates for subjects diagnosed in the period 1981–2000 using log-rank tests and Poisson regression models.Main Outcome Measures: Cumulative probability of OAG-related blindness and population incidence of blindness within 10 years of diagnosis.Results: Probability of glaucoma-related blindness in at least 1 eye at 20 years decreased from 25.8% (95% confidence interval [CI], 18.5–32.5) for subjects diagnosed in 1965–1980 to 13.5% (95% CI, 8.8–17.9) for subjects diagnosed in 1981–2000 (P = 0.01). The population incidence of blindness within 10 years of the diagnosis decreased from 8.7 per 100 000 (95% CI, 5.9–11.5) for subjects diagnosed in 1965–1980 to 5.5 per 100 000 (95% CI, 3.9–7.2) for subjects diagnosed in 1981–2000 (P = 0.02). Higher age at diagnosis was associated with increased risk of progression to blindness (P < 0.001).Conclusions: The 20-year probability and the population incidence of blindness due to OAG in at least 1 eye have decreased over a 45-year period from 1965 to 2009. However, a significant proportion of patients still progress to blindness despite recent diagnostic and therapeutic advancements.Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Read more →

Circularity Index as a Risk Factor for Progression of Geographic Atrophy – Corrected Proof

by  •  • 0 Comments

Objective: To develop a parameter that can assess the relative rate of progression of geographic atrophy (GA) based on the hypothesis that noncircular configuration of the atrophic lesion may be a risk factor for enlargement.Design: Cohort study.Participants: Digitized color photographs of 593 eyes with GA from the Age-Related Eye Disease Study (AREDS).Methods: A novel parameter called the “Geographic Atrophy Circularity Index” (GACI) was developed on the basis of area and perimeter measurements to categorize the irregularity of the shape of GA. The GACI ranges from 0.0 to 1.0 and is categorized into 3 groups: 0.25 (very irregular), 0.25 to <0.75 (partly irregular), and ≥0.75 (circular).Main Outcome Measures: Growth rate of GA.Results: The mean growth rate in the 3 categories was 0.40 (±0.18), 0.36 (±0.30), and 0.21 (±0.22) mm/year, respectively (P < 0.001). By adjusting for known confounders, baseline area, duration of GA, and configuration, GACI categories were significantly associated with increased growth rate of GA (P < 0.001).Conclusions: The GACI was associated with the progression rate of GA and may be a useful measure for clinical trial eligibility. The association also suggests that enlargement of GA may be related to the extent of the junctional zone of damaged retinal pigment epithelium, which increases with noncircularity for a given GA area.Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Read more →

Visual Impairment Corrected Via Cataract Surgery and 5-Year Survival in a Prospective Cohort – Corrected Proof

by  •  • 0 Comments

Purpose: To compare mortality risk between cataract surgical patients with corrected and persistent visual impairment.Design: Cohort study.Methods: A total of 1864 consecutive patients, aged ≥64 years, undergoing phacoemulsification surgery at Westmead Hospital were followed annually for 5 years postoperatively. Visual impairment status in the surgical eye was categorized as none (presenting visual acuity [VA], ≥20/40), mild (VA <20/40-20/60), or moderate-severe (VA <20/60). All-cause mortality was obtained from the Australian National Death Index.Results: Of 901 patients with moderate-severe visual impairment before surgery, 60.4% (n = 544), 15.5% (n = 140), and 24.1% (n = 217) had no, mild, or moderate-severe visual impairment in the surgical eye, respectively, 1 month postoperatively. Age-standardized 5-year mortality rates were nonsignificantly lower in patients with either mild (24.7%, 95% confidence interval [CI] 16.5%-32.9%) or no visual impairment (24.1%, 95% CI 19.9%-28.4%) post surgery compared to that in patients whose moderate-severe visual impairment persisted (30.6%, 95% CI 23.3%-37.9%). After adjusting for age, sex, smoking, body mass index, and individual comorbid conditions, such as hypertension, diabetes, angina, myocardial infarction, stroke, transient ischemic attack, and kidney disease, patients with no visual impairment 1 month postoperatively had a lower mortality risk (HR 0.73, 95% CI 0.52-1.01) compared to those with persistent moderate-severe visual impairment after surgery. This finding was significant (HR 0.71, 95% CI 0.51-0.99) after additional adjustment for number of medications taken (continuous variable) and number (≥3 vs <3) of comorbid conditions.Conclusion: Correcting moderate-severe visual impairment in older patients with phacoemulsification surgery was associated with a lower mortality risk, compared to surgical patients whose visual impairment persisted postoperatively.

Read more →

Grouped Retinae and Tapetal Cups in some Teleostian Fish: Occurrence, Structure, and Function

by  •  • 0 Comments

Publication date: Available online 22 October 2013
Source:Progress in Retinal and Eye Research
Author(s): Mike Francke , Moritz Kreysing , Andreas Mack , Jacob Engelmann , Anett Karl , Felix Makarov , Jochen Guck , Mathias Kolle , Hartwig Wolburg , Roland Pusch , Gerhard von der Emde , Stefan Schuster , Hans-Joachim Wagner , Andreas Reichenbach
This article presents a summary and critical review of what is known about the ‘grouped retina’, a peculiar type of retinal organization in fish in which groups of photoreceptor cell inner and outer segments are arranged in spatially separated bundles. In most but not all cases, these bundles are embedded in light-reflective cups that are formed by the retinal pigment epithelial cells. These cups constitute a specialized type of retinal tapetum (i.e., they are biological ‘mirrors’ that cause eye shine) and appear to be optimized for different purposes in different fishes. Generally, the large retinal pigment epithelial cells are filled with light-reflecting photonic crystals that consist of guanine, uric acid, or pteridine depending on species, and which ensure that the incoming light becomes directed onto the photoreceptor outer segments. This structural specialization has so far been found in representatives of 17 fish families; of note, not all members of a given family must possess a grouped retina, and the 17 families are not all closely related to each other. In many cases (e.g., in Osteoglossomorpha and Aulopiformes) the inner surface of the cup is formed by three to four layers of strikingly regularly shaped and spaced guanine platelets acting as an optical multilayer. It has been estimated that this provides an up to 10fold increase of the incident light intensity. In certain deep-sea fish (many Aulopiformes and the Polymixidae), small groups of rods are embedded in such ‘parabolic mirrors’; most likely, this is an adaptation to the extremely low light intensities available in their habitat. Some of these fishes additionally possess similar tapetal cups that surround individual cones and, very likely, also serve as amplifiers of the weak incident light. In the Osteoglossomorpha, however, that inhabit the turbid water of rivers or streams, the structure of the cups is more complex and undergoes adaptation-dependent changes. At dim daylight, probably representing the usual environmental conditions of the fish, the outer segments of up to 30 cone cells are placed at the bottom of the cup where light intensity is maximized. Strikingly, however, a large number of rod receptor cells are positioned behind each mirroring cup. This peculiar arrangement (i) allows vision at deep red wavelenghts, (ii) matches the sensitivity of rod and cone photoreceptors, and (iii) facilitates the detection of low-contrast and color-mixed stimuli, within the dim, turbid habitat. Thus, for these fish the grouped retina appears to aid in reliable and quick detection of large, fast moving, biologically relevant stimuli such as predators. Overall, the grouped retina appears as a peculiar type of general retinal specialization in a variety of fish species that is adaptive in particular habitats such as turbid freshwater but also the deep-sea.The authors were prompted to write this review by working on the retina of Gnathonemus petersii; the data resulting from this work (Landsberg et al., 2008; Kreying et al., 2012) are included in the present review.

Read more →

Defects of the Lamina Cribrosa in Eyes with Localized Retinal Nerve Fiber Layer Loss – Corrected Proof

by  •  • 0 Comments

Objective: To determine whether focal abnormalities of the lamina cribrosa (LC) are present in glaucomatous eyes with localized retinal nerve fiber layer (RNFL) defects.Design: Cross-sectional, observational study.Participants: We analyzed 20 eyes of 14 subjects with localized RNFL defects detected by masked grading of stereophotographs and 40 eyes of 25 age-matched healthy subjects recruited from the Diagnostic Innovations in Glaucoma Study at the University of California, San Diego.Methods: All eyes had stereoscopic optic disc photography and in vivo LC imaging using enhanced depth imaging optical coherence tomography (EDI-OCT). Two masked graders identified focal LC defects defined by a standardized protocol using 48 radial scan EDI-OCT images. The kappa coefficient was calculated as a measure of the reliability of interobserver agreement.Main Outcome Measures: The number of focal LC defects and the relationship between the location of LC defects and the location of localized RNFL defects.Results: Of 20 eyes with a localized RNFL defect, 15 (75%) had ≥1 LC defect compared with only 1 of 40 healthy eyes (3%). There were 13 eyes with localized RNFL defects that had 1 LC defect, 1 eye with 2 LC defects, and 1eye with 3 LC defects. The largest area LC defect was present in a radial line EDI-OCT scan corresponding with a localized RNFL defect in 13 of 15 eyes (87%). There was good agreement between graders as to whether an eye had an LC defect (kappa = 0.87; 95% confidence interval [CI], 0.73–1.00; P<0.001) and the location of the largest defect (kappa = 0.72; 95% CI, 0.44–1.00; P<0.001).Conclusions: Focal defects of the LC were frequently visible in glaucomatous eyes with localized RNFL defects. Focal abnormalities of the LC may be associated with focal retinal nerve fiber damage.Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references.

Read more →

Risk Factors for Amblyopia in the Vision in Preschoolers Study – Corrected Proof

by  •  • 0 Comments

Objective: To evaluate risk factors for unilateral amblyopia and for bilateral amblyopia in the Vision in Preschoolers (VIP) study.Design: Multicenter, cross-sectional study.Participants: Three- to 5-year-old Head Start preschoolers from 5 clinical centers, overrepresenting children with vision disorders.Methods: All children underwent comprehensive eye examinations, including threshold visual acuity (VA), cover testing, and cycloplegic retinoscopy, performed by VIP-certified optometrists and ophthalmologists who were experienced in providing care to children. Monocular threshold VA was tested using a single-surround HOTV letter protocol without correction, and retested with full cycloplegic correction when retest criteria were met. Unilateral amblyopia was defined as an interocular difference in best-corrected VA of 2 lines or more. Bilateral amblyopia was defined as best-corrected VA in each eye worse than 20/50 for 3-year-olds and worse than 20/40 for 4- to 5-year-olds.Main Outcome Measures: Risk of amblyopia was summarized by the odds ratios and their 95% confidence intervals estimated from logistic regression models.Results: In this enriched sample of Head Start children (n = 3869), 296 children (7.7%) had unilateral amblyopia, and 144 children (3.7%) had bilateral amblyopia. Presence of strabismus (P < 0.0001) and greater magnitude of significant refractive errors (myopia, hyperopia, astigmatism, and anisometropia; P < 0.00001 for each) were associated independently with an increased risk of unilateral amblyopia. Presence of strabismus, hyperopia of 2.0 diopters (D) or more, astigmatism of 1.0 D or more, or anisometropia of 0.5 D or more were present in 91% of children with unilateral amblyopia. Greater magnitude of astigmatism (P < 0.0001) and bilateral hyperopia (P < 0.0001) were associated independently with increased risk of bilateral amblyopia. Bilateral hyperopia of 3.0 D or more or astigmatism of 1.0 D or more were present in 76% of children with bilateral amblyopia.Conclusions: Strabismus and significant refractive errors were risk factors for unilateral amblyopia. Bilateral astigmatism and bilateral hyperopia were risk factors for bilateral amblyopia. Despite differences in selection of the study population, these results validated the findings from the Multi-Ethnic Pediatric Eye Disease Study and Baltimore Pediatric Eye Disease Study.Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Read more →

Intravitreal Aflibercept for Treatment-Resistant Neovascular Age-Related Macular Degeneration – Corrected Proof

by  •  • 0 Comments

Objective: To assess the effectiveness of intravitreal aflibercept in patients with neovascular age-related macular degeneration (AMD) previously resistant to treatment with other anti–vascular endothelial growth factor agents.Design: Prospective, open-label, noncontrolled, registered clinical trial.Participants: Forty-nine patients with treatment-resistant neovascular AMD.Intervention: A dose of 2 mg intravitreal aflibercept was administered as 3 initial loading doses every 4 weeks (week 0, week 4, and week 8), followed by further injections every 8 weeks (weeks 16 and 24) across a 24-week period in total. All patients underwent a complete ophthalmic examination, including measurement of Early Treatment Diabetic Retinopathy Study (ETDRS) best-corrected visual acuity (BCVA), intraocular pressure assessment, adverse event monitoring, and spectral-domain optical coherence tomography at every visit. Baseline fluorescein angiography and indocyanine green angiography also were performed.Main Outcome Measures: Outcomes assessed included proportions of patients with a gain or loss of more than 5 ETDRS letters and a decrease or increase in central retinal thickness (CRT) of more than 150 μm at week 24 compared with baseline, change in mean BCVA and CRT between baseline and week 24, and descriptive safety data.Results: The BCVA improved and CRT was reduced significantly at all follow-up visits compared with baseline (P < 0.001), with a mean improvement of 6.9 letters of BCVA and a decrease of 89.4 μm in CRT at week 24. Spacing of injections from every 4 weeks to 8 weeks resulted in an increase of 37.4 μm in CRT (P < 0.001); however, this was not correlated with a significant change in vision. There was 1 (2%) patient who lost more than 5 ETDRS letters, and 27 (55%) patients who gained more than 5 letters. Two (4%) patients had a more than 150 μm increase in CRT at week 24, and 10 (20%) patients showed a decrease in CRT of more than 150 μm.Conclusions: Intravitreal aflibercept is effective in previously treatment-resistant neovascular AMD. Further follow-up is required to determine whether these improvements can be maintained.Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references.

Read more →

Assessment of the Quality of Glaucoma Referral Letters Based on a Survey of Glaucoma Specialists and a Glaucoma Guideline – Corrected Proof

by  •  • 0 Comments

Objective: To assess the quality of glaucoma referral letters and to report on the results of a survey of glaucoma specialists about referral letter content.Design: Cross-sectional study.Participants: A survey of 135 glaucoma specialists and audit of 200 consecutive referral letters to a tertiary glaucoma unit.Methods: An online questionnaire was sent to members of the Canadian and American Glaucoma Societies asking what they considered the most important data to be included in a glaucoma referral. Consecutive referral letters to a tertiary glaucoma unit were assessed for legibility and content on the basis of the survey results and information items in current guidelines.Main Outcome Measures: Survey outcome and proportion of included content items in referral letters.Results: The survey revealed that the top 5 most important data that glaucoma specialists would like to be included in a referral letter for progressive glaucoma were serial visual fields (VFs), current glaucoma therapy, current intraocular pressure (IOP), maximum IOP, and serial disc imaging. These items often were omitted in the referral letters audited. A total of 200 referral letters were assessed, 46% from ophthalmologists, 42% from optometrists, 10% from family practitioners, and 2% from other sources. Reasons for referral were diagnosis of glaucoma (37%), unstable glaucoma (25%), angle assessment (17%), and others (21%). Some 26% of the referral letters were deemed illegible (18% from ophthalmologists vs. 6% from optometrists; P < 0.01). Degree of urgency was mentioned in 27% of referrals. Optometrists were more likely than ophthalmologists to provide visual acuity (VA), IOP, refraction, and VFs (P < 0.01 for each). Some 24% of referrals for progression included more than 10 of the 14 information points suggested by the Canadian glaucoma guidelines, and 34% included fewer than 8 of the 14 points.Conclusions: Referral letters frequently did not include important information, with 34% of referral letters deemed substandard. Optometrist referrals were better than ophthalmologist referrals in terms of content and legibility. A checklist of clinical details for referring physicians is suggested, which includes maximum and current IOP, disc evaluation, serial VFs, and serial disc imaging.Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Read more →