Diagnostic accuracy and variability of autorefraction by the Tracey Visual Function Analyzer and the Shin-Nippon NVision-K 5001 in relation to subjective refraction.

PURPOSE: To determine the accuracy of distance autorefractions obtained by two 'open field' devices, the Tracey Visual Function Analyzer and the Shin-Nippon NVision-K 5001, by comparison with subjective refraction. METHODS: Both eyes of 50 healthy phakic participants underwent subjective refraction. Autorefractions were then performed on undilated pupils using the Tracey and a modified Shin-Nippon autorefractor and these were repeated within 50 days. Agreement with subjective refraction was calculated for sphere, mean spherical equivalent (MSE) and cylindrical vectors J(0) and J(45). Intratest and intertest variability were also evaluated. RESULTS: The mean age of the participants was 37.4 years. Subjective refraction MSE ranged from -6.25 D to +3.62 D, mean -0.49 D +/- 1.79 D. Bias between subjective refraction and Tracey was -0.001 D, +0.045 D, +0.017 D, and -0.015 D for sphere, MSE, J(0) and J(45) respectively; these were not significant. Bias between subjective refraction and Shin-Nippon was +0.004 D, +0.033 D, +0.106 D, and -0.021 D; only the J(0) vector was significantly different (p < 0.0001) although this difference was small. Intratest variability for Tracey was low, measured at 0.189 D for sphere and 0.178 for MSE, and for the Shin-Nippon 0.099 D and 0.086 D respectively. Tracey intertest variability revealed small, statistically significant bias for sphere and MSE (+0.071 D and +0.070 D, p = 0.011, 0.013). Shin-Nippon reproducibility showed no significant bias. CONCLUSIONS: Autorefraction measurements captured by both the Tracey and Shin-Nippon devices agree well with subjective refraction. The Shin-Nippon shows lower intratest variability.

Intravitreal triamcinalone acetonide for refractory uveitic cystoid macular oedema: longterm management and outcome.

PURPOSE: To establish the role of intravitreal triamcinalone acetonide (TA) in the long term management of refractory uveitic cystoid macular oedema (CMO) and to determine the long term visual outcome in these patients. METHOD: This is a retrospective observational case series. All patients had resistant CMO and active inflammation. The primary outcome measure was complete resolution of CMO on ocular coherence tomography. Visual acuity and intraocular pressure were also monitored. Twelve eyes of twelve patients received 2 (n = 10) to 4 (n = 2) mg of intravitreal TA. All had previously been unresponsive to orbital floor steroids. Fluorescein angiography was performed where indicated. RESULTS: There was complete resolution of CMO in all patients. Nine patients had improvement in acuity at there final follow up (mean follow up 40.5 months). Seven had improved by 2 lines (58%). In 3 patients there was no visual improvement. These 3 failed to respond to re-treatment. Five other patients were re-treated because of recurring CMO and deteriorating VA (median time to re-treatment 4 mths). The mean number of re-treatments for this group with orbital floor TA was three. 41.6% of patients developed ocular hypertension (33.8 mhg mean). One required a trabeculectomy. CONCLUSIONS: 2 mg of intravitreal TA is effective even in cases of resistant uveitic CMO. Although re-treatment is often required, the initial response to treatment can be maintained by subsequent orbital floor steroid injections.

Steroid prophylaxis in eyes with uveitis undergoing phacoemulsification.

AIM: To compare the efficacy of two preoperative steroid regimens for cataract surgery in patients with uveitis. METHODS: 40 uveitis patients with cataract underwent phacoemulsification and intraocular lens (IOL) implantation. Preoperatively they were randomised into two groups: group 1 (20 patients) received a single dose of intravenous methylprednisolone (15 mg/kg) half an hour before surgery, and group 2 (20 patients) received a 2 week course of oral prednisolone (0.5 mg/kg) which was tapered postoperatively. Preoperatively patients had aqueous flare and cells measured with the Kowa laser flare meter. On days 1, 7, 28, and 90 aqueous flare and cells were measured, and on days 7 and 90 fluorescein angiography was performed to determine the incidence of cystoid macular oedema (CMO). RESULTS: At all postoperative visits the mean increase in flare was greater for group 1 (intravenous steroid). Patients with posterior synechiae had greater blood-aqueous barrier damage (BAB) postoperatively. There were no statistically significant differences in logMAR visual acuity and incidences of CMO between the two groups at 7 and 90 days. CONCLUSION: A 2 week course of oral prednisolone, tapered postoperatively, produced a better recovery of the BAB than a single dose of intravenous methylprednisolone and is thus the recommended preoperative regimen.

A mathematical model of factors that influence the performance of accommodative intraocular lenses.

In this work a mathematical model of capsule movement during pseudophakic accommodation is described to allow identification and evaluation of factors that may explain the variation in effect of accommodative intraocular lenses (IOLs) between patients. The model assumes that increasing vitreous pressure pushes the lens capsule forward as a circular diaphragm and that this movement is from a fixed fulcrum. With an IOL in situ, the capsule is taken to have a non-uniform thickness due to the presence of the anterior capsulorhexis. The model assumes a uniform capsular elasticity and ignores contributions from cellular elements such as posterior capsule opacification. Using our model and a regression formula to calculate capsular bag size, taking into account axial length and keratometry values, we are able to predict accommodative effect in individual patients. By simple geometry we have developed a mathematical model to identify variables that are important in pseudophakic accommodation. It provides the basis for the development of a more complex model that would address the movement of a lens taking into account the influence of the zonular system during accommodation.

Effect of intraocular lens haptic compressibility on the posterior lens capsule after cataract surgery.

PURPOSE: To evaluate the effect of intraocular lens (IOL) haptic compressibility on the posterior capsule after cataract surgery. SETTING: Teaching hospital, London, United Kingdom. METHODS: In this randomized prospective study, 60 patients had standardized phacoemulsification with in-the-bag placement of a poly(methyl methacrylate) (PMMA) (Storz P497UV) or hydrogel (Storz Hydroview H60M) IOL. Both IOLs had PMMA haptics of identical configuration and length. The IOL haptic compressibility was measured in air and then during incubation in saline at 37 degrees C over 1 month. Digital retroillumination imaging was performed 1, 7, 28, 90, 180, 360, and 720 days postoperatively. The presence and duration of postoperative capsule folds were recorded and correlated with the haptic compressibility measurements, lens epithelial cell (LEC) growth patterns on the posterior capsule at 6 months, and the extent of posterior capsule opacification. RESULTS: On the first postoperative day, 21 patients (88%) in the Hydroview group had posterior capsule folds that persisted in 12 patients (50%) for 2 years. Nineteen patients (68%) in the PMMA group had folds at day 1 (P =.01), with 1 patient (3%) still having folds at 1 month (P =.0002) and no patient having folds at 3 months. At 6 months, 11 patients (46%) in the Hydroview group and no patient in the PMMA group had LEC growth in the direction of the folds. The PMMA IOLs showed a greater decrease in haptic compressibility during incubation. CONCLUSIONS: Haptic compressibility should be an important consideration in IOL design. The results suggest that to avoid posterior capsule folds, the compressibility should be less than 2.5 mN.

The effect of polymethylmethacrylate and acrysof intraocular lenses on the posterior capsule in patients with a large capsulorrhexis.

PURPOSE: We have previously shown that patients who have a capsulorrhexis larger than the diameter of a polymethylmethacrylate (PMMA) intraocular lens (IOL) rapidly develop increased posterior capsule opacification (PCO), in effect, producing an example of enhanced PCO. This study focuses on the influence of AcrySof IOLs on this process. METHODS: Phacoemulsification was performed on two groups of patients. The first consisted of 38 patients with a large capsulorrhexis of 6-7 mm who received a 5.5-mm PMMA IOL. The second group of 32 patients had identical surgery and a 5.5-mm MA30 AcrySof IOL was implanted. On days 1,14, 28, 90, 180, and 360, high resolution digitized retroillumination images were taken of the posterior capsule. The PCO area was measured by image analysis at 90, 180, and 360 days. Wrinkling of the posterior capsule was determined at 90 days, and the progression or regression of lens epithelial cell (LEC) proliferation was established by examination of serial images at 28 and 180 days. RESULTS: At 90 days, 79% of the patients with PMMA IOLs had moderate to severe wrinkling of the posterior capsule, whereas the patients with AcrySof IOLs had none (P <.001). The percentage of PCO area was 69% for the PMMA IOLs and 24% for the AcrySof IOL group at 360 days (P <.0001). In the PMMA group, LEC progression occurred in 77%, LEC growth was stable in 15%, and LEC regression occurred in only 8%, compared to 69% of patients with AcrySof IOLs (P <.0001). CONCLUSIONS: In patients with a rhexis larger than the IOL, AcrySof IOLs potentially can prevent capsular wrinkling and cause less PCO than a PMMA IOL with a similar rhexis size. The LEC regression occurs with AcrySof between 28 and 180 days. The reasons for this are discussed.

Effect of optic size on posterior capsule opacification: 5.5 mm versus 6.0 mm AcrySof intraocular lenses.

PURPOSE: To determine the effect of intraocular lens (IOL) optic diameter on posterior capsule opacification (PCO) using digital retroillumination images. SETTING: Eye Department, St. Thomas' Hospital, London, United Kingdom. METHODS: In this prospective study, 60 patients with senile cataract had routine phacoemulsification by a single surgeon and received standardized medication. The patients were divided into 2 equal groups. The first group received a 5.5 mm 3-piece AcrySof IOL (MA30BM, Alcon) inserted in the bag. The second group received a 6.0 mm 3-piece AcrySof IOL (MA60BM, Alcon). Retroillumination images were obtained 1, 30, 90, 180, and 360 days postoperatively. The percentage area of PCO was calculated objectively by dedicated software at 90, 180, and 360 days. At 1 day, the degree of capsulorhexis-IOL contact was determined by inspecting the images. RESULTS: Throughout the follow-up, there was less PCO in the 6.0 mm optic group than in the 5.5 mm optic group, and the difference reached significance 1 year postoperatively (P =.0017). At 1 year, the median percentage of PCO was 1.5% (95% confidence interval [CI] 1.4-5.3) in the 6.0 mm group and 6.9% (95% CI 5.8-18.0) in the 5.5 mm group. CONCLUSIONS: A larger IOL optic diameter was associated with less PCO.

Intravitreal triamcinolone for uveitic cystoid macular edema: an optical coherence tomography study.

PURPOSE: To investigate the use of intravitreal injection of triamcinolone acetonide (TA) for the treatment of refractory uveitic cystoid macular edema (CME). DESIGN: Prospective, nonrandomized, self-controlled comparative trial. PARTICIPANTS: Six patients with chronic CME resistant to treatment with systemic steroids, orbital floor steroids, and cyclosporine A. Three patients were followed for more than 1 year, and the other three for between 3 and 9 months. INTERVENTION: Injection of 2 mg of TA into the vitreous cavity. TESTING: Optical coherence tomography scanning of the fovea before and after injection and logarithmic minimal angle of resolution visual acuity. MAIN OUTCOME MEASURES: Visual acuity, retinal thickness, cystoid space height, and intraocular pressure. RESULTS: There was complete anatomic resolution of CME in five of the six cases within 1 week after injection. Cystoid spaces began to return between 6 weeks and 3 months after injection. Two patients with longer term follow-up responded to further orbital floor steroid injection and had no CME 1 year later. One patient had raised intraocular pressure develop, requiring a trabeculectomy. Mean improvement in visual acuity after 12 months was 0.27 (range, 0.14-0.42). CONCLUSIONS: Complete anatomic and, to some extent, functional recovery can be induced by intravitreal TA despite long-term refractory inflammatory CME. Optical coherence tomography aids in the management of these cases.

Quantification of posterior capsular opacification in digital images after cataract surgery.

PURPOSE: To describe a software program developed to provide an objective assessment of the amount of posterior capsular opacification (PCO) in high-resolution digital images of the posterior capsule after cataract surgery. METHODS: Images are analyzed by a set protocol of defining the area of the posterior capsule, removing the Purkinje light reflexes by intensity segmentation, contrast enhancement, filtering to enhance low-density PCO, and variance analysis using a co-occurrence matrix to assess texture. The accuracy of the system was tested for validity and repeatability. RESULTS: The software developed has been demonstrated to be an objective method of quantifying PCO. In validation tests, the image analysis-derived measure of PCO showed good agreement with clinically derived measures of PCO. Clinicians assessed PCO on a computer screen image and also under slit lamp examination (Pearson correlation coefficient for both methods >0.92). The entire acquisition and analysis system was demonstrated to have a confidence limit for 2 SDs of 9.8% for group data. CONCLUSIONS: This system is capable of producing an accurate and reproducible measure of PCO that is relevant to assessing techniques of PCO prevention.

Quantitative volume replacement in the correction of post-traumatic enophthalmos.

We describe a technique to correct enophthalmos that involves measurement of the volume of the injured orbit followed by an accurate replacement of this volume with an autogenous bone graft. Twelve consecutive patients were treated with this technique and all but one showed an improvement in enophthalmos. Four of the seven with diplopia improved after the operation.

Double-masked prospective ocular safety study of a lens epithelial cell antibody to prevent posterior capsule opacification.

PURPOSE: To evaluate the intraocular safety of an immunoconjugate (MDX-RA) developed to prevent posterior capsule opacification (PCO) in human eyes. SETTING: St. Thomas's Hospital Eye Department, London, United Kingdom. METHODS: Twenty-six patients had phacoemulsification and implantation of an intraocular lens (IOL). All were randomly allocated at the end of surgery to receive a 0.1 mL placebo or 0.1 mL of the immunotoxin MDX-RA intracamerally. Two doses of the drug were tested: 8 patients with a low dose (50 units), 9 patients with a high dose (100 units), and 9 with placebo. Follow-up at days 1, 14, 30, 60, 90, and 180 consisted of visual acuity measured by the Early Treatment of Diabetic Retinopathy Study test, contrast sensitivity, aqueous flare, specular microscopy of the IOL's anterior surface, and corneal endothelial counts. The percentage area of PCO was measured from retroillumination images of the posterior capsule. RESULTS: There was no decrease in corneal endothelial cell count in toxin-treated patients. Early postoperative flare, anterior chamber cell count, and corneal pachymetry were higher in toxin-treated patients. The median percentage area of PCO at 1 year was 32.0 in the placebo group, 3.8 in the low-dose group, and 7.4 in the high-dose group (P = .06). CONCLUSION: This prospective, randomized, placebo-controlled trial confirmed that MDX-RA is safe for intraocular use and is of potential value for further clinical trials of the prevention of PCO.

Posterior capsular opacification with hydrogel, polymethylmethacrylate, and silicone intraocular lenses: two-year results of a randomized prospective trial.

PURPOSE: To compare the visual outcome, percentage of posterior capsular opacification, and laser capsulotomy rates with polymethylmethacrylate, silicone, and hydrogel intraocular lens implants at 1 and 2 years postoperatively. METHODS: Ninety-three eyes of 93 patients were randomized to receive a polymethylmethacrylate, silicone, or hydrogel intraocular lens implant. A standardized surgical protocol was followed by a single surgeon using phacoemulsification with capsulorhexis; any patients with surgical complications were excluded, and all patients received standardized medication and follow-up. Patients were examined at days 1 and 7, months 1, 3, and 6, and years 1 and 2 after surgery. At each assessment, best-corrected logMAR visual acuity and Pelli-Robson contrast sensitivity were measured. Posterior capsular opacification was objectively assessed by digital retroillumination imaging with the use of a dedicated software program and calculated as the percentage area of opacified capsule. Laser capsulotomy was performed if the eye had lost 2 lines of visual acuity with a clinically opaque capsule. RESULTS: At 2 years postoperatively, the mean percentage area of posterior capsular opacification for hydrogel lenses was 63%; for polymethylmethacrylate, 46%; and for silicone, 17%. Hydrogel intraocular lenses were associated with 17% more posterior capsule opacification than were polymethylmethacrylate lenses (95% confidence interval, 1-33; P =. 037) and 45% more than were silicone lenses (95% confidence interval, 33-58; P <.0001) at 2 years. Polymethylmethacrylate lenses had 28% more posterior capsule opacification than silicone lenses (95% confidence interval, 13-43; P <.0001) at 2 years. Twenty-eight percent of patients with hydrogel intraocular lenses required an Nd:YAG laser posterior capsulotomy at 2 years, compared with 14% with polymethylmethacrylate, whereas no patients with silicone lenses needed a capsulotomy (P =.014). Visual acuity was not significantly different among the three groups, but patients with silicone intraocular lenses had significantly better contrast sensitivity than those with hydrogel lenses (P =.046). CONCLUSIONS: Intraocular lenses made of this specific hydrogel were associated with a significantly higher degree of posterior capsular opacification and more laser capsulotomies than polymethylmethacrylate and silicone intraocular lenses.

Comparison between optical coherence tomography and fundus fluorescein angiography for the detection of cystoid macular edema in patients with uveitis.

PURPOSE: To compare optical coherence tomography (OCT) with fundus fluorescein angiography (FFA) for the detection of cystoid macular edema (CME) in patients with uveitis. DESIGN: Prospective comparative observational series. PARTICIPANTS: One hundred twenty-one eyes of 58 patients with uveitis of varied causes (seven patients were studied twice). TESTING: Patients with suspected CME underwent OCT scanning followed by FFA at the same visit. MAIN OUTCOME MEASURES: Detection and distribution of macular edema. RESULTS: One hundred eight eyes had similar results on both OCT and FFA in that 67 eyes had CME and 41 eyes had no CME. In 10 eyes subretinal fluid was detected on OCT but not FFA. Five of these eyes had CME on FFA but not OCT. Three other eyes had CME that was detected by FFA but not by OCT. Compared with FFA, the OCT sensitivity for detecting CME was 96% (including the eyes with subretinal fluid), and the OCT specificity was 100%. CONCLUSIONS: OCT is as effective at detecting CME as is FFA but is superior in demonstrating axial distribution of fluid.

Cystoid macular edema after phacoemulsification: relationship to blood-aqueous barrier damage and visual acuity.

PURPOSE: To ascertain the incidence of cystoid macular edema (CME) after phacoemulsification and its relationship to blood-aqueous barrier damage and visual acuity. SETTING: A British teaching hospital. METHODS: A prospective trial was performed to document the incidence of CME after routine phacoemulsification with continuous curvilinear capsulorhexis. LogMAR visual acuity and laser flare were measured using the KOWA FC 1000 laser cell-flare meter preoperatively and 1, 14, 30, and 60 days postoperatively. At day 60, a standardized fluorescein angiogram was performed and graded by masked observers. RESULTS: The rate of angiographic CME on day 60 was 19%. Visual acuity at each visit was significantly worse in the CME group (P < .05). The flare and cell values at days 14, 30, and 60 were higher in the CME group at day 60; however, the difference was not statistically significance (P > .05). CONCLUSIONS: The incidence of CME after routine phacoemulsification was 19%. Patients with CME at day 60 had significantly worse visual acuity than those who did not from the first postoperative day throughout the follow-up. There was a trend for patients who had CME at day 60 to have more postoperative inflammation.

The effect of capsulorhexis size on posterior capsular opacification: one-year results of a randomized prospective trial.

PURPOSE: Posterior capsular opacification is the most common surgically related cause of reduced vision after cataract surgery. We studied the effect of capsulorhexis size on the pattern and severity of posterior capsular opacification. METHODS: In this prospective study 75 patients underwent standardized phacoemulsification with capsulorhexis and in-the-bag placement of a 5.5-mm polymethylmethacrylate intraocular lens implant. The patients were randomly assigned to receive either a small capsulorhexis of 4.5 to 5 mm to lie completely on the intraocular lens optic or a large capsulorhexis of 6 to 7 mm to lie completely off the lens optic. Patients were examined at days 1, 14, 30, 90, and 180 and at year 1 with logMAR visual acuity assessment, Pelli-Robson contrast sensitivity testing, anterior chamber flare and cell measurement, and high-resolution digital retroillumination imaging of the posterior capsule. The pattern of posterior capsular opacification was determined, and the percentage area of posterior capsular opacification was calculated for each image with dedicated image analysis software. RESULTS: Large capsulorhexes were associated with significantly more wrinkling of the posterior capsule and worse posterior capsular opacification than small capsulorhexes. At 1 year the average percentage area of posterior capsular opacification was 32.7% for small capsulorhexes (95% confidence interval, 19.8 to 45.6) and 66.2% for large capsulorhexes (95% confidence interval, 57.7 to 74.6) (P = .0001). The patients with large capsulorhexes had significantly poorer visual acuities and a trend toward worse contrast sensitivities. CONCLUSION: This study demonstrated significantly greater wrinkling and opacification of the posterior capsule and worse visual acuity with large capsulorhexes than with small capsulorhexes. In cataract surgery with a polymethylmethacrylate intraocular lens, a small capsulorhexis with the edge completely on the surface of the implant is preferable to a large capsulorhexis in reducing posterior capsular opacification.

In vitro protein adsorption to 2 intraocular lens materials.

PURPOSE: To study in vitro protein adsorption to poly(methyl methacrylate) (PMMA) and foldable AcrySof intraocular lenses (IOLs). SETTING: Department of Ophthalmology, United Medical and Dental Schools of Guy's and St. Thomas' Hospitals, London, United Kingdom. METHODS: Poly(methyl methacrylate) (Alcon Surgical, model MC60BM) and AcrySof (Alcon Surgical, model MA60BM) IOLs were incubated in physiological concentrations of radiolabeled albumin or fibronectin at 37 degrees C for periods between 5 minutes and 1 week. The IOLs were removed and rinsed in buffered saline, and the amount of adsorbed protein was calculated by measuring the radioactivity with scintillation spectrometry. RESULTS: The adsorption of both proteins occurred rapidly over the first 2 hours; the rate of adsorption was concentration dependent. Quantitative differences were found: PMMA lenses bound significantly greater quantities of albumin. Initial fibronectin adsorption to both materials was similar, but increased adsorption to AcrySof IOLs was found at days 1 and 7. CONCLUSIONS: The differences in protein absorption to PMMA and AcrySof IOLs in vitro may contribute to the differences in the biological response to these IOLs, including the lower rates of posterior capsule opacification associated with acrylic lenses.