D. Alistair H. Laidlaw

Acute Retinal Necrosis: The Effects of Intravitreal Foscarnet and Virus Type on Outcome

PURPOSE To study the effects of intravitreal foscarnet and the clinical differences between varicella zoster virus (VZV) and herpes simplex virus (HSV) induced acute retinal necrosis (ARN). DESIGN Retrospective comparative case series. PARTICIPANTS Eighty-one eyes of 74 patients. METHODS A retrospective case note analysis was performed in 2 tertiary referral centers. MAIN OUTCOME MEASURES Presenting and final visual acuity, and progression to retinal detachment. RESULTS Thirty-three eyes had HSV-ARN and 48 had VZV-ARN. The average age for HSV-ARN was 34 years and 51 for VZV-ARN (P<0.001). Visual acuity on presentation was similar (P = 0.48), but a larger proportion had better vision (> or =20/60) in the HSV-ARN group (52%) than the VZV-ARN group (35%). A greater proportion of eyes with poor vision (< or =20/200) was found at the 12-month follow-up in the VZV-ARN group (60%) compared with the HSV-ARN group (35%). A greater degree of visual loss in the VZV-ARN group (0.4 logarithm of the minimum angle of resolution [logMAR]) compared with the HSV-ARN group (0.04 logMAR) was detected (P = 0.016). Retinal detachment was 2.5-fold more common in VZV-ARN (62%) compared with HSV-ARN (24%). When comparing eyes treated with (n = 56) and without (n = 25) intravitreal foscarnet, there was a 40% lower rate in retinal detachment (53.6% vs 75.0%) for VZV-ARN (P = 0.23). The numbers with HSV-ARN were too small for analysis. CONCLUSIONS The results support the difference of outcome in HSV-ARN and VZV-ARN. Therefore, viral identification serves as a key to predicting outcome in these patients. Intravitreal foscarnet seems to be a useful adjunct for the treatment of ARN in that it reduced rate of retinal detachment.

Scleral hydraulic conductivity and macromolecular diffusion in patients with uveal effusion syndrome

PURPOSE To determine whether uveal effusion syndrome (UES) is caused by altered scleral permeability to water and large molecules. METHODS Transscleral water movement was measured using surgically removed sclera clamped in a modified Ussing chamber and connected to a water column set at intraocular pressure. Sclera was also clamped between two hemichambers, and transscleral diffusion of FITC-dextrans (4.4-77 kDa) was measured with a spectrophotometer. Clinical data were prospectively collected using postal questionnaires. RESULTS Ten patients (mean age, 63 years; mean spherical equivalent, +4.7 D) had a median preoperative visual acuity of 0.20 that improved to 0.33 after surgery. Nine eyes showed visual improvement, three worsened, and two were unchanged. Histology showed disorganization of collagen fibrils, with amorphous deposits expanding the interfibrillary spaces. The mean thickness (+/-1 SD) of the excised scleral specimens was 585 +/- 309 microm, and the mean specific hydraulic conductivity was 23.9 +/- 27.5 x 10(-14) cm(2), compared with 5.8 +/- 3.9 x 10(-14) cm(2) in age-matched control specimens (P = 0.068). Three specimens had hydraulic conductivity above the 95% CI of the controls. Control eyes showed a significant reduction in diffusion coefficient (D) with age. Eyes had a mean D of 5.69 +/- 5.35 x 10(-8) cm(2) x s(-1), similar to control eyes (6.14 +/- 2.40 x 10(-8) cm(2) x s(-1), 20 kDa dextran). In one eye, the result was higher than the 95% CI of the control; in three, it was lower. CONCLUSIONS UES is not caused by reduced scleral hydraulic conductivity, which tends to be higher than expected. Reduced macromolecular diffusion may impede the normal transscleral egress of albumin with subsequent osmotic fluid retention in some, but not all eyes.

Dye extrusion technique (DE-TECH): occult retinal break detection with subretinal dye extrusion during vitrectomy for retinal detachment repair.

Objective: To investigate the effectiveness of a new technique for the identification of occult retinal breaks in vitrectomy retinal detachment repair. Dye Extrusion Technique involves injection of sub retinal dye and extrusion through the unidentified breaks using perfluorocarbon liquid. Method: Retrospective case note analysis. Main outcome measures: rate of break detection, rate of use of local retinopexy, and short-term gas tamponade alone; Secondary outcomes: anatomical success at 3 months with no long-term tamponade, final visual acuity, progression of proliferative vitreoretinopathy. Results: Thirty-eight percent of eyes had proliferative vitreoretinopathy of grade C1 or worse. Twenty-five percent underwent primary retinal detachment repair surgery. The remainder underwent repeat operations for previously failed surgery. Breaks were found in 89% of eyes and 81% underwent only local retinopexy and gas tamponade. The overall anatomical success rate was 85% (40/47) which included four cases in which the retina was fully attached awaiting removal of silicone oil. No cases had unexplained loss of vision. No progression of proliferative vitreoretinopathy was noted. Conclusions: Results suggest that Dye Extrusion Technique may be an effective technique for the identification of occult retinal breaks and may facilitate simple techniques of detachment repair. No evidence of retino-toxicity from the use of trypan blue was found but the study had limited power to detect adverse effects.

Air-gas exchange reevaluated: clinically important results of a computer simulation.

PURPOSE The primary aim of this study was to evaluate the efficiency of air-gas exchange techniques and the factors that influence the final concentration of an intraocular gas tamponade. Parameters were varied to find the optimum method of performing an air-gas exchange in ideal circumstances. METHODS A computer model of the eye was designed using 3D software with fluid flow analysis capabilities. Factors such as angular distance between ports, gas infusion gauge, exhaust vent gauge and depth were varied in the model. Flow rate and axial length were also modulated to simulate faster injections and more myopic eyes, respectively. The flush volume of gas required to achieve a 97% intraocular gas fraction concentration were compared. RESULTS Modulating individual factors did not reveal any clinically significant difference in the angular distance between ports, exhaust vent size, and depth or rate of gas injection. In combination, however, there was a 28% increase in air-gas exchange efficiency comparing the most efficient with the least efficient studied parameters in this model. The gas flush volume required to achieve a 97% gas fill also increased proportionately at a ratio of 5.5 to 6.2 times the volume of the eye. CONCLUSIONS A 35-mL flush is adequate for eyes up to 25 mm in axial length; however, eyes longer than this would require a much greater flush volume, and surgeons should consider using two separate 50-mL gas syringes to ensure optimal gas concentration for eyes greater than 25 mm in axial length.

Computerized Repeating and Averaging Improve the Test-Retest Variability of ETDRS Visual Acuity Measurements: Implications for Sensitivity and Specificity

PURPOSE The goals of this study were to investigate the effectiveness of computerized repeating and averaging of visual acuity measurements in reducing test-retest variability (TRV) and to estimate the increase in sensitivity and specificity that would be achieved in diagnosing visual acuity change. METHODS Timed, paired ETDRS chart and computerized acuity mean measurement (CAMM) were performed in 100 subjects. CAMM(n) scores were the running mean of consecutive measurements. Bland-Altman methods were used to calculate 95% ranges for TRV. RESULTS The 95% TRV range of ETDRS measurements and the CAMM score after 6 (CAMM6) measurements were, respectively, 8 and 5.7 ETDRS letters (P = 0.02). CAMM6 offered a pragmatically optimum tradeoff between reduced TRV and test time. A measured change of 5 letters or more in the absence of true change was observed in 13% (95% CI, 8%-21%) with the ETDRS chart and 4% (95% CI, 2%-10%) with CAMM6 measurements. To achieve ≥95% test sensitivity (assuming 95% test specificity), change criteria of 15 and 11 letters must be set with an ETDRS chart and CAMM6, respectively. CAMM6 measurement times were longer (mean 234 seconds vs. 74 seconds) for the ETDRS chart. CONCLUSIONS Compared with the current gold standard, computerized repeating and averaging of acuity measurements improve specificity and sensitivity when identifying true changes. The 160-second increase in test time should be set against the considerable economic and clinical benefits that may result.

Day 1 postoperative intraocular pressure spike in vitreoretinal surgery (VDOP1)

Purpose:  To classify the clinical characteristics that might identify patients who may not require next‐day follow‐up following routine vitreoretinal intervention.

Macular displacement following rhegmatogenous retinal detachment repair

Aims To investigate the incidence of macula displacement and symptoms of distortion following rhegmatogenous retinal detachment (RRD) repair, quantify the displacement where seen and further characterise the nature of the displacement. Methods Consecutive patients undergoing primary RRD repair were assessed postoperatively with fundus autofluorescence and optical coherence tomography imaging, and the extent of macula displacement quantified using a novel means. Findings were examined for correlations with symptoms and pre-operative features. Results Macula displacement was evident postoperatively in 72% of 32 consecutive fovea-involving detachments treated with vitrectomy and gas. It was also evident in 5/17 foveal-sparing cases treated with vitrectomy and gas and in two of two patients with fovea-involving detachments treated with vitrectomy and oil. There was a significant correlation between the presence of macula displacement and symptoms of distortion in the early postoperative period (p=0.013). Symptomatic patients described bending of lines with or without objects appearing smaller or narrower in the operated eye. Quantifying the displacement demonstrated that the extent of displacement was associated with distance from the optic disc (p=0.005) and the extent of retinal detachment. Conclusions Displacement of the macula is common following RRD repair and heterogeneous in nature. Most affected patients are symptomatic in the early postoperative period.

Spectral Domain Optical Coherence Tomography Findings in a Case Series of Patients with Bilateral Diffuse Uveal Melanocytic Proliferation

Bilateral diffuse uveal melanocytic proliferation (BDUMP) is a rare paraneoplastic disorder characterized by bilateral serous retinal detachment with degeneration of the retinal pigment epithelium (RPE). The condition commonly occurs in females with gynecological carcinoma or males with lung malignancy, although several other cancer sites have been described. Furthermore, the condition may occur as the first sign of yet undiscovered malignancy. Our understanding of BDUMP has increased significantly in the last 5 years. Affected patients have recently been shown to possess cultured melanocyte elongation and proliferation (CMEP) factor in the IgG fraction of the serum, explaining the efficacy of plasma exchange in the treatment of the condition. Furthermore, BDUMP-associated dermal and conjunctival melanocytic proliferations have been shown to have minimal malignant potential. Although several authors have reported histological retinal findings in BDUMP, these may be complicated by preparation artifact. We present, for the first time to our knowledge, a mini case series of spectral domain optical coherence tomography (OCT) findings in BDUMP. CASE REPORTS

Morphision: A method for subjective evaluation of metamorphopsia in patients with unilateral macular pathology (i.e., full thickness macular hole and epiretinal membrane)

Background: Lack of clinical tests to quantify spatial components of distortion in patients with full thickness macular holes (FTMH) and epiretinal membranes (ERM). Aim: To develop a test for subjective evaluation of visual distortion in the central visual field around fixation in patients with unilateral FTMH or ERM. Settings and Design: Prospective case-control study carried out at tertiary referral center. Materials and Methods: Twenty-five patients with unilateral macular disease (13 macular epiretinal membranes, 12 full-thickness macular holes), and nine controls (without ocular pathology) underwent ophthalmological examination with logMAR ETDRS visual acuity, near vision and contrast sensitivity assessed. Macular optical coherence tomography and metamorphopsia assessment using Morphision test was also carried out. This test consists of a set of modified Amsler charts for detection, identification, and subjective quantification of visual distortion in the central visual field around fixation. Morphision test content and construct validity, and reliability (test-retest method) were evaluated. Sixteen patients completed an unstructured survey on test performance and preference. Results: Every patient with unilateral FTMH or ERM identified a particular chart using Morphision test (content validity). None of the normal subjects without symptoms of metamorphopsia identified any distortion (construct validity). Test-retest showed a 100% consistency for frequency and 67% for amplitude. The mean amplitude difference between measurements was 0.02 degrees (SD = 0.038). The coefficient of repeatability was 0.075. There was a correlation between Morphision amplitude score and visual acuity and contrast sensitivity, individually. Conclusions: Morphision test allowed detection and subjective quantification of metamorphopsia in the clinical setting in our patients with unilateral macular epiretinal membranes and full thickness macular holes.

Risk factors for visual impairment in patients with sickle cell disease in London.

Purpose Dramatically improved health care in recent years has increased the life expectancy of patients with sickle cell disease (SCD) as well as the prognosis for its ocular complications. We sought to identify risk factors for visual impairment in patients with SCD in London 4 decades after Goldbergs seminal studies. Methods Patients 16 years and older with SCD (genotypes HbSS, HbSC, HbSβ-thalassemia) attending hematology and ophthalmology services were offered ocular examination. Retinopathy was graded according to the Goldberg classification. Visual impairment was defined as corrected distance visual acuity of 20/40 or poorer. Results In total, 182 eyes of 182 patients (mean ± SD age, 37.2 ± 12.8 years; female, 65.9%) were included. Women were significantly older than men (mean ± SD age, 38.8 ± 13.1 vs 34.2 ± 11.8 years; p = 0.0174). There was no difference in mean age of each genotype group (p>0.15). Risk factors for sight-threatening proliferative sickle retinopathy (PSR) were age over 35 years (odds ratio [OR] 2.01; 95% confidence interval [CI] 1.05-3.89; p = 0.0359) and HbSC genotype (OR 4.06; 95% CI 2.07-7.98; p<0.0001). Although visual impairment was related to the presence of sight-threatening PSR (OR 7.23; 95% CI 1.50-35.0; p = 0.0138), it was not related to hemoglobin genotype (p>0.50). Conclusions We present the largest study of ocular findings in SCD in the United Kingdom. Sight-threatening PSR is a risk factor for visual impairment, but hemoglobin genotype status is not.