Factors associated with variability in retinal nerve fiber layer thickness measurements obtained by optical coherence tomography.

OBJECTIVE: To identify factors associated with variability in retinal nerve fiber layer (RNFL) thickness measurements obtained by optical coherence tomography (OCT). DESIGN: Retrospective observational case series. PARTICIPANTS: One hundred fifty consecutive patients with known or suspected glaucomatous optic nerve damage undergoing OCT imaging for RNFL thickness measurement. METHODS: One eye with known or suspected glaucoma from each patient was scanned twice within the same visit using the Stratus OCT's fast nerve fiber layer thickness acquisition protocol. For each scan, the average RNFL thickness, signal strength (a measure of the amount of light reflecting back from the retina), and analysis confidence (AC, a measure of the quality of the data as reported by the OCT software) were recorded. Retinal nerve fiber layer thickness measurements of the initial and repeat scans for each case were compared, and the difference in thickness measurements was correlated with difference in signal strength, AC (either low or normal), and the average RNFL thickness. MAIN OUTCOME MEASURE: Difference in RNFL thickness. RESULTS: The mean difference in RNFL thickness between the initial and repeat scans was 10 microns (12.5%; range, 0.04-86.15 microns). Difference in signal strength between initial and repeat scans positively correlated with the difference in RNFL thickness (Spearman correlation coefficient = 0.44; P<0.001), whereas the average nerve fiber layer thickness negatively correlated with the difference in RNFL thickness (Spearman correlation coefficient = -0.25; P = 0.002). The presence of a scan with low AC was associated with a lower average RNFL thickness and a greater difference in RNFL thickness between the initial and repeat scans. CONCLUSIONS: Signal strength variability, low AC, and low RNFL thickness are associated with variability in RNFL thickness measurements obtained by Stratus OCT. Comparability of RNFL thickness measurements between visits may be improved if scans of similar signal strengths without low AC are obtained. This is especially important for patients with moderate glaucomatous optic nerve damage and for patients from whom good quality scans are not obtainable.

Intravitreal triamcinolone acetonide for the treatment of immune recovery uveitis macular edema.

PURPOSE: To evaluate the use of intravitreal triamcinolone (IVTA) for the treatment of macular edema secondary to immune recovery uveitis (IRU) in patients with AIDS. DESIGN: Prospective, consecutive, interventional case series. PARTICIPANTS: Eight eyes of 7 patients receiving 13 injections. METHODS: Prospective, consecutive, interventional case series of 13 injections involving 8 eyes in 7 patients who underwent an intravitreal injection of 20 mg decanted triamcinolone acetate for fluorescein angiographically proven IRU-related macular edema. MAIN OUTCOME MEASURES: The primary outcome measure was vision (using the Early Treatment Diabetic Retinopathy Study chart). Other outcome measures included fluorescein angiography and optical coherence tomography. RESULTS: Visual acuity improved at all time points and was statistically significant at the 1-month and 3-month follow-up examinations. The average visual improvement was 3 lines at 3 months. Retinal volume and thickness improvement were statistically significant at all time points. All patients had a minimum follow-up of 9 months, and there were no cases of cytomegalovirus reactivation. CONCLUSIONS: Previous studies showed that treatment with sub-Tenon repository steroids for the treatment of macular edema of IRU was only marginally effective. However, the current study shows that IVTA can be an effective short-term treatment for macular edema secondary to IRU in patients with AIDS. Longer follow-up is needed to assess the durability of the effect and to monitor for longer-term complications and outcomes.

Assessment of retinal function in patients with HIV without infectious retinitis by multifocal electroretinogram and automated perimetry.

PURPOSE: To determine if multifocal electroretinogram (mfERG) testing shows abnormalities that correspond to perimetric defects in HIV positive patients without infectious retinitis. METHODS: We studied three groups of patients: HIV negative controls, HIV high CD4 nadir patients (lowest CD4 T cell count is over 100) and low CD4 nadir patients (below 100 for over 6 months). Twenty-six HIV positive eyes and 16 HIV negative control eyes were studied by mfERG. A subset of 10 eyes also underwent computerized perimetry for comparison. We analyzed mfERG by hexagons as well as by quadrants and rings. RESULTS: Of 103 hexagon locations there was no significant difference in the amplitudes P1 and N1 (nV/degree) between the three studied groups (p>0.05), similarly, the latencies were not different (p>0.05). All eyes with significant visual field defects at the 0.01 and 0.005 level (Humphrey pattern deviation; 24-2) were compared to mfERG amplitudes and latencies at those locations-there were no corresponding defects in mfERG data (p>0.2). CONCLUSION: In the era of HAART there are still demonstrable visual field defects and other evidence of damage to the retinal nerve fiber layer in HIV patients. Our mfERG studies show that the damage appears to affect the inner retina, the outer retina is spared. Further studies of inner retinal structure and function are indicated to elucidate this process.

Esterified estrogens combined with methyltestosterone raise intraocular pressure in postmenopausal women.

PURPOSE: To investigate the effect of esterified estrogens combined with methyltestosterone (EECM) (Estratest, Solvay, Pharmaceuticals, Inc, Baudette, Minnesota, USA) on intraocular pressure (IOP) in postmenopausal women. DESIGN: Observational case series. METHODS: The IOP of 13 consecutive postmenopausal women with dry eye syndrome were recorded before and during EECM therapy (1.25 mg of esterified estrogens and 2.5 mg of methyltestosterone for several months). RESULTS: The mean IOP increased from a baseline of 15.0 mm Hg before treatment to 18.2 mm Hg on EECM therapy (P < .0001) after a median duration of 11.3 months (range, 0.9 to 24 months). The increase in IOP was statistically significant at the 0.05 level of significance within three months and continued over 12 months. Two patients whose pressures increased (>4 mm Hg) returned to baseline levels after EECM was discontinued. CONCLUSIONS: Esterified estrogens combined with methyltestosterone produce a clinically significant increase in IOP in postmenopausal women with dry eye syndrome.

Effect of a novel octapeptide urokinase fragment, A6, on experimental choroidal neovascularization in the monkey.

PURPOSE: To evaluate the inhibitory effects of a urokinase-derived octapeptide, A 6, on laser-induced choroidal neovascularization (CNV) in monkeys. METHODS: Twenty female cynomolgus monkeys were randomly grouped into weekly or monthly A 6 treatment groups, each consisting of 10 animals. CNV was induced in both eyes by perimacular laser treatment. In each right eye, a single 22.25-mg A 6 dose (monthly group) or 4 22.25-mg A 6 doses each week (weekly group) were given by intravitreal injections. Each left eye received phosphate buffer on the same schedule. Monkeys were observed for 4 weeks by ophthalmic examinations, color photography, and fluorescein angiography. RESULTS: Weekly treated eyes had a 35% reduction of CNV compared with controls (P = 0.23). In contrast, monthly treated eye had a 71% reduction of CNV compared with controls (P = 0.0009). There was no evidence of toxicity at both clinical and pathologic examinations. CONCLUSIONS: Intravitreal A 6 injections effectively inhibited CNV in cynomolgus monkeys without evidence of toxicity. The overall reduction in CNV was greater for monthly treated eyes than for weekly treated eyes. This study suggests that A 6 has promise as a local antiangiogenic treatment of CNV. Further work is indicated to evaluate the potential role of A 6 in therapy for human CNV associated with age-related macular degeneration.

Errors in retinal thickness measurements obtained by optical coherence tomography.

OBJECTIVE: To report the frequency and severity of optical coherence tomography (OCT) retinal thickness measurement errors and to describe parameters that predict these errors. DESIGN: Observational case series. PARTICIPANTS: Two hundred consecutive patients undergoing OCT imaging. METHODS: One eye (primary) from each of 200 consecutive patients undergoing Stratus OCT imaging (Carl Zeiss Meditec, Dublin, CA) with radial lines or fast macular thickness-based acquisition protocols was selected for review by 2 graders. On each of the line scans, graders evaluated the position of the automated retinal boundary lines (inner retinal surface and retinal pigment epithelium band) used by the OCT machine for thickness calculations and graded the positioning on a 6-point subjective, categorical error scale to generate an error score. The presence of thickness errors was correlated with various parameters, including the analysis confidence assessment reported by the OCT software, disease diagnosis, retinal morphologic features, the foveal center thickness standard deviation (FCTSD), and the FCTSD-to-foveal center thickness (FCT) ratio. MAIN OUTCOME MEASURE: Average OCT retinal thickness error score. RESULTS: Errors of retinal boundary detection and thickness measurement were observed in 92% of eyes, but were severe in only 13.5% of eyes. The identification of an error or low analysis confidence by the OCT software was strongly associated with the severity of the retinal thickness errors. A higher FCTSD-to-FCT ratio and presence of subretinal fluid also were associated with more severe errors. Retinal cysts and a diagnosis of retinal vascular disease such as diabetic macular edema were less likely to be associated with significant errors. CONCLUSIONS: Retinal thickness measurement errors occur frequently with current OCT segmentation and analysis algorithms. Severe errors are more frequent in eyes with subretinal pathologic features, but generally are detected by the OCT software. A high FCTSD-to-FCT ratio (>0.1) also may alert the clinician to the possibility of thickness errors. Clinical studies, particularly those pertaining to subretinal diseases, should consider these errors when incorporating OCT imaging in the study design.

Results of silicone oil removal in patients with cytomegalovirus retinitis related retinal detachments.

PURPOSE: To evaluate the percentage and risk indicators leading to retinal redetachment in HIV (human immunodeficiency virus) patients with CMV (cytomegalovirus) retinitis related retinal detachments that were repaired with silicone oil, and then subsequently underwent oil removal. DESIGN: Retrospective, noncomparative interventional case series. METHODS: The study cohort consisted of a series of 15 eyes in 14 patients with HIV and CMV retinitis with a retinal detachment (RD) repaired with silicone oil at a single center and followed from the time of the CMV retinitis diagnosis through the time of silicone oil removal. Patient- and eye-specific data regarding demographic and clinical characteristics were collected retrospectively and statistical analyses were performed to compare differences between the eyes that had retinal detachments versus the eyes that remained attached following removal of silicone oil. RESULTS: Eight eyes (53%) redetached after a median of 4.0 months following oil removal. Cataract surgery performed at the time of oil removal was a statistically significant risk factor for redetachment (P = .01). There was a trend for lower CD4 levels to be associated with a higher risk of retinal redetachment. The use of a scleral buckle at the time of surgery (initial RD repair or at the time of oil removal) did not reduce the risk of redetachment. CONCLUSIONS: Approximately half of the eyes with CMV related retinal detachment may safely undergo oil removal. The risk factor for redetachment was simultaneous cataract extraction at the time of silicone oil removal. There was also a trend for lower CD4 levels to be associated with a higher risk of retinal redetachment.