Category: Peer-reviewed

Characteristics of Peripapillary Choroidal Cavitation Detected by Optical Coherence Tomography

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Purpose:
To evaluate the clinical features of peripapillary choroidal cavitation (PCC) detected by optical coherence tomography (OCT).

Design:
Retrospective, observational case series.

Participants:
One hundred twenty-two eyes from 83 patients diagnosed with PCC by OCT database review were included in this study.

Methods:
Stereoscopic color fundus photographs from eyes with PCC were reviewed by 2 independent ophthalmologists. They were masked to the refractive error, axial length, and OCT findings.

Main Outcome Measures:
Chart review and data analysis included gender, age, best-corrected visual acuity (BCVA), refractive error, axial length, clinical appearance of the peripapillary area, and associated funduscopic abnormalities.

Results:
One hundred twenty-two eyes with PCC from 83 patients were analyzed. Among the patients, 41.8% were men and 58.2% were women. The mean age was 48.2±12.6 years and mean BCVA in logarithm of the minimum angle of resolution units was 0.23±0.43. The mean refractive error in spherical equivalent was −9.03±5.11 diopters (D) and mean axial length (AL) was 27.36±2.09 mm. With respect to refractive error, 90 eyes (73.8%) were highly myopic (≥–6.00 D), 24 eyes (19.7%) had low myopia ( 1.00 D). Forty eyes (32.8%) with PCC had AL of less than 26.50 mm (mean, 25.11±1.07 mm; range, 22.51–26.42 mm). Patients with eyes with PCC that had low myopia, were emmetropic, and were hyperopic also were significantly older than patients with highly myopic eyes (P<0.05). Stereoscopic fundus photographs demonstrated a yellow-orange, localized, well-circumscribed peripapillary lesion in 57 (46.7%) eyes with PCC. A PCC with opening was observed in 14 (26.4%) of 53 eyes with excavated myopic conus and in 5 (7.2%) of 69 eyes without excavated myopic conus (P<0.05).

Conclusions:
This study demonstrated that peripapillary choroidal cavitation is common and not exclusive to highly myopic eyes. The funduscopic finding of a yellow-orange peripapillary abnormality may not be evident in all eyes with demonstrable PCC by OCT. Although its pathogenesis and pathologic significance require further investigation, PCC may be a degenerative change in aging eyes.

Financial Disclosure(s):
The author(s) have no proprietary or commercial interest in any materials discussed in this article.

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Cost-Effectiveness of Descemet’s Stripping Endothelial Keratoplasty versus Penetrating Keratoplasty

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Purpose:
Selective endothelial transplantation in the form of Descemet’s stripping endothelial keratoplasty (DSEK) is rapidly replacing traditional full-thickness penetrating keratoplasty (PK) for endothelial disease. An incremental cost-effectiveness analysis was performed to determine whether the benefits of DSEK are worth the additional costs.

Design:
Retrospective cohort study.

Participants:
Patients at the Singapore National Eye Center, a tertiary eye center in Singapore, with Fuchs’ dystrophy or bullous keratopathy who underwent either PK or DSEK.

Intervention:
Patients underwent either PK (n = 171) or DSEK (n = 93) from January 2001 through December 2007. Data were collected from inpatient and outpatient notes corresponding to the time immediately before the procedure to up to 3 years after.

Main Outcome Measures:
Improvements in best spectacle-corrected visual acuity were used to calculate the increase in quality-adjusted life years (QALYs) 3 years after the procedure. This was combined with hospital charges (a proxy for costs) to determine incremental cost-effectiveness ratios (ICERs) comparing PK with no intervention and DSEK with PK.

Results:
Three-year charges for DSEK and PK were $7476 and $7236, respectively. The regression-adjusted improvement in visual acuity for PK relative to no intervention was −0.613 logarithm of the minimum angle of resolution (logMAR) units (P<0.001), and for DSEK relative to PK, it was −0.199 logMAR units (P = 0.045). The regression-adjusted marginal gain in utility for PK relative to no intervention was 0.128 QALYs (P<0.001) and for DSEK relative to PK was 0.046 QALYs (P = 0.031). This resulted in ICERs of $56 409 per QALY for PK relative to no intervention and $5209 per QALY for the more expensive DSEK relative to PK.

Conclusions:
If the goal is to maximize societal health gains given fixed resources, DSEK should be the preferred strategy. For a fixed budget, it is possible to achieve greater QALY gains by providing DSEK to as many patients as possible (and nothing to others), rather than providing PK.

Financial Disclosure(s):
The author(s) have no proprietary or commercial interest in any materials discussed in this article.

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Corneal Thickness in Keratoconus: Comparing Optical, Ultrasound, and Optical Coherence Tomography Pachymetry

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Purpose:
To compare the central and peripheral pachymetry measurements determined using Orbscan IIz (Bausch & Lomb, Rochester, NY), Visante optical coherence tomography (OCT; Carl Zeiss Meditec, Dublin, CA), and RTVue OCT (Oculus Technologies, Wynwood, WA) with ultrasound pachymetry in eyes with established keratoconus and to evaluate the agreement between them.

Design:
Evaluation of diagnostic technologies.

Participants:
One hundred six eyes of 67 consecutive patients with a clinical diagnosis of keratoconus ranging in age from 12 to 40 years.

Methods:
Central corneal thickness (CCT) was determined by all the 4 techniques. Peripheral corneal thicknesses were determined using Orbscan IIz, Visante OCT, and RTVue at 8 points (superior, inferior, temporal, nasal, superior-temporal, inferior-temporal, superior-nasal, and inferior-nasal) all in the 5.0- to 7.0-mm arcuate zone.

Main Outcome Measures:
Central and peripheral keratoconus thickness.

Results:
Ultrasound pachymetry determined significantly higher CCT values than Orbscan IIz (P<0.001), Visante (P<0.001), and RTVue (P = 0.037), with a mean ± standard deviation difference of 14±3 μm, 13±2 μm, and 5±3 μm, respectively. The mean CCT difference was minimal (1±3 μm; P = 0.69) between the Orbscan IIz and Visante. A strong correlation was found (r>0.80) between all the CCT measurement techniques. Orbscan IIz significantly overestimated the peripheral thickness compared with the rest, and the mean differences ranged between 21 and 60 μm. Mean peripheral thickness differences between RTVue and Visante OCT always remained less than 20 μm. Weak correlations and larger limits of agreement were found between the techniques in thinner and peripheral zones.

Conclusions:
Orbscan IIz, Visante, RTVue, and ultrasound pachymetry show high correlation, although Orbscan IIz and Visante significantly underestimated CCT measurements compared with ultrasound pachymetry in keratoconus. Orbscan IIz significantly overestimated peripheral corneal thickness compared with RTVue and Visante.

Financial Disclosure(s):
The author(s) have no proprietary or commercial interest in any materials discussed in this article.

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Associations of Anisometropia with Unilateral Amblyopia, Interocular Acuity Difference, and Stereoacuity in Preschoolers

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Purpose:
To evaluate the relationship of anisometropia with unilateral amblyopia, interocular acuity difference (IAD), and stereoacuity among Head Start preschoolers using both clinical notation and vector notation analyses.

Design:
Multicenter, cross-sectional study.

Participants:
Three- to 5-year-old participants in the Vision in Preschoolers (VIP) study (n = 4040).

Methods:
Secondary analysis of VIP data from participants who underwent comprehensive eye examinations, including monocular visual acuity testing, stereoacuity testing, and cycloplegic refraction. Visual acuity was retested with full cycloplegic correction when retest criteria were met. Unilateral amblyopia was defined as IAD of 2 lines or more in logarithm of the minimum angle of resolution (logMAR) units. Anisometropia was defined as a 0.25-diopter (D) or more difference in spherical equivalent (SE) or in cylinder power and 2 approaches using power vector notation. The percentage with unilateral amblyopia, mean IAD, and mean stereoacuity were compared between anisometropic and isometropic children.

Main Outcomes Measures:
The percentage with unilateral amblyopia, mean IAD, and mean stereoacuity.

Results:
Compared with isometropic children, anisometropic children had a higher percentage of unilateral amblyopia (8% vs. 2%), larger mean IAD (0.07 vs. 0.05 logMAR), and worse mean stereoacuity (145 vs. 117 arc sec; all P<0.0001). Larger amounts of anisometropia were associated with higher percentages of unilateral amblyopia, larger IAD, and worse stereoacuity (P<0.001 for trend). The percentage of unilateral amblyopia increased significantly with SE anisometropia of more than 0.5 D, cylindrical anisometropia of more than 0.25 D, vertical and horizontal meridian (J0) or oblique meridian (J45) of more than 0.125 D, or vector dioptric distance of more than 0.35 D (all P<0.001). Vector dioptric distance had greater ability to detect unilateral amblyopia than cylinder, SE, J0, or J45 (P<0.001).

Conclusions:
The presence and amount of anisometropia were associated with the presence of unilateral amblyopia, larger IAD, and worse stereoacuity. The threshold level of anisometropia at which unilateral amblyopia became significant was lower than current guidelines. Vector dioptric distance is more accurate than spherical equivalent anisometropia or cylindrical anisometropia in identifying preschoolers with unilateral amblyopia.

Financial Disclosure(s):
The author(s) have no proprietary or commercial interest in any materials discussed in this article.

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Progression Pattern of Initial Parafoveal Scotomas in Glaucoma

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Objective:
To characterize the progression pattern of initial parafoveal scotomas (IPFSs) using cross-sectional and longitudinal 10-2 visual field (VF) data.

Design:
Retrospective, observational study.

Participants:
Glaucoma patients with an IPFS in either hemifield based on 2 reliable 24-2 Swedish interactive threshold algorithm standard VFs (≥3 adjacent points with P<0.05 within the central 10° of fixation, 1 point or more with P<0.01 lying at the innermost paracentral points, and no scotoma outside the central 10°) and at least 2 10-2 VFs (first and last VFs 1 year or more apart).

Methods:
To simulate a cohort with an extended follow-up, eyes with an IPFS were divided into subgroups based on the severity of glaucoma using their 10-2 VF pattern standard deviation (PSD). Cross-sectional data were used to create an average pattern deviation map that was generated by averaging pattern deviation map values of 10-2 VF point-by-point within each subgroup. Longitudinal data (eyes with 5 or more 10-2 VFs) was used to perform pointwise linear regression analysis of pattern deviation values. Patterns of IPFS progression were identified from these cross-sectional and longitudinal assessments.

Main Outcome Measures:
Average pattern deviation maps (cross-sectional) and maps of progression rates (longitudinal) in different disease severity subgroups.

Results:
Eighty eyes (80 patients) and 40 eyes (40 patients) with an IPFS were included for cross-sectional and longitudinal analyses, respectively. The mean age ± standard deviation, 24-2 VF mean deviation, and 24-2 VF PSD for all eyes were 63±10 years, −3.27±2.18 dB, and 5.46±2.40 dB, respectively. Based on maps generated in both cross-sectional and longitudinal analyses, IPFS in the superior hemifield had an arcuate pattern initially that later deepened approximately 3° to 5° above fixation. The scotoma then elongated toward the physiologic blind spot and spread toward the nasal periphery, sparing the area corresponding to the papillomacular bundle. The IPFS in the inferior hemifield had a similar pattern, but was slightly farther from fixation.

Conclusions:
Superior and inferior IPFS have a similar characteristic pattern of progression, although the latter tend to be farther from fixation. Understanding these patterns should help in the management of such patients and in improving VF testing algorithms.

Financial Disclosure(s):
Proprietary or commercial disclosure may be found after the references.

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