Use of Optomap for retinal screening within an eye casualty setting.

AIM: To compare nurse-guided Optomap retinal imaging with examination by an eye casualty officer, in detecting clinically significant peripheral retinal lesions in patients with retinal symptoms. METHODS: 219 patients presenting to eye casualty with retinal symptoms (flashing lights and floaters) were recruited. Retinal images were taken with the Optomap imaging system, and graded by an independent masked ophthalmologist. The findings from the Optomap and casualty officer were compared with a gold-standard examination with scleral indentation performed by a retinal specialist. We calculated the sensitivity and specificity of the Optomap and casualty officer. RESULTS: The final analysis included 205 eyes of 187 patients. The sensitivity of the Optomap for detecting retinal detachment (n = 7) was 100% (95% CI 59-100%), the same as the casualty officer. For retinal holes/tears (n = 18) the Optomap sensitivity was 33% (13-59%), compared with 67% (41-87%) for the casualty officer. Combining all retinal lesions (n = 52), the sensitivity was 62% (47-75%) and 73% (59-84%), with specificity 96% (92-99%) and 98% (94-100%) for the Optomap and casualty officer respectively. CONCLUSION: The Optomap detects retinal detachments successfully but, due to limitations in the optics, is not able to accurately detect retinal holes and tears.

Treatment of retinal breaks with large-spot diode laser photocoagulation.

A new technique is described for treating peripheral retinal breaks using large-spot, diode laser retinopexy. A large-spot (1.2 to 3.0 mm) diode laser (810 nm) was used to treat patients with breaks in attached retina. Powers between 800 and 1,200 mW produced a uniform retinal photocoagulation beyond the break margins. Patients were observed monthly until an adequate chorioretinal scar had formed. Eleven eyes were treated using this technique. Satisfactory retinopexy was obtained in all cases. The efficiency of large-spot diode laser photocoagulation for retinal breaks and its advantages over conventional laser and cryopexy techniques justifies further studies into this technique.

Results 28 months following transpupillary thermotherapy for classic and occult choroidal neovascularization in patients with age-related macular degeneration.

BACKGROUND AND OBJECTIVE: To report the outcome of patients 28 months following treatment with transpupillary thermotherapy (TTT) for classic and occult choroidal neovascularization (CNV) secondary to age-related macular degeneration. PATIENTS AND METHODS: A nonrandomized pilot trial of 36 eyes of 33 patients was performed. Eyes with angiographically defined CNV, 11 predominantly classical and 25 predominantly occult, were treated with large spot diode laser (810 nm) TTT for 1 minute, the end point being no or minimal visible change. Outcome was assessed with best-corrected LogMAR visual acuity, clinical examination, and fluorescein angiography. RESULTS: Patients were observed for a mean of 28.7 months (range, 18 to 40 months). The mean change in LogMAR visual acuity for predominantly classic membranes was -1.91 (standard deviation [SD] = 4.3) and 5 of 11 (45.5%) eyes had a loss of 3 or more LogMAR lines. Predominantly classic membranes were closed in 9 of 11 eyes and stabilized in 2 of 11 eyes. The mean change in LogMAR visual acuity for predominantly occult membranes was -1.48 (SD = 6.3) and 10 of 25 (40%) patients had a loss of 3 lines or more. Predominantly occult CNV was stabilized in 25 of 25 cases, and recurrence developed in 2 of 25 cases; one of the latter developed classic CNV. CONCLUSIONS: The medium-term results for patients treated with TTT for both occult and classic CNV show good stability, with little visual loss and few recurrences. These data confirm the original findings of this study.

Kinetic anaesthesia for laser surgery.

PURPOSE: Local anaesthetic is widely used in ophthalmic surgery and more recently in vitreoretinal surgery. Akinesia is a useful effect of local anaesthetic blocks, but there are situations where some residual globe movements are of benefit. We looked to see whether reducing the volume of anaesthetic solution used in a block could retain some kinesia while achieving good analgesia. METHODS: We compared two groups of patients undergoing panretinal photocoagulation (PRP) with an indirect laser. The control group received 5 ml of anaesthetic solution in a single injection by a standard intraconal technique; a second group received a lower volume of solution by the same technique. We recorded the adequacy of anaesthesia and the amount of residual kinesia for the two groups. Differences between groups were analysed using the Student's t-test and chi(2) tests. RESULTS: The low-volume group received an average of 2.8 ml, compared to 5 ml in the control group. There was no significant difference in the adequacy of analgesia achieved, however 16/18 (89%: 95% confidence intervals (CI)=81.5-96.3%) of the low-volume group had good perioperative kinesia compared to just 3/21 (14%: 95% CI=6.6-21.9%) of the controls (P<0.001). CONCLUSIONS: We have shown that low-volume intraconal blocks retain some perioperative kinesia without compromising their analgesic effect.

Effect of video display on the grading of diabetic retinopathy.

PURPOSE: Digital images are increasingly being used in ophthalmology. These may be viewed either on thin-film transistor (TFT) or on cathode-ray tube (CRT) displays. However, there is little data showing which is superior. In this study, we compared the performance of CRT and TFT displays for grading of both compressed and uncompressed images of diabetic retinopathy. METHODS: A total of 49 35 mm transparencies of diabetic retinopathy were scanned and compressed. The images comprised 17 with no retinopathy, eight with background, five with preproliferative, and 19 with proliferative retinopathy. Four levels of compression were used: 0, 70, 80, and 90%. A total of 196 randomised images were presented to two masked graders using both TFT and CRT displays under uniform lighting conditions, 2 months apart. The grade of retinopathy was assessed. Statistical analysis of grading accuracy was performed using receiver operator characteristic curves of sensitivity and specificity and the Stuart-Maxwell test for paired, nonparametric data. RESULTS: Both displays showed high sensitivity and specificity for the detection of any retinopathy. For the specific grade of retinopathy, the CRT performed slightly better with a sensitivity of 0.80 for uncompressed images, compared with 0.75 using the TFT. Compression reduced these sensitivities to 0.73 on the CRT and 0.63 on the TFT. Grading of uncompressed images magnified to four times their original size was more accurate on the TFT. CONCLUSIONS: Grading on both displays met sensitivity and specificity criteria proposed by Diabetes UK (formerly British Diabetic Association) for screening of diabetic retinopathy. The CRT generally performed slightly better than the TFT in relation to the detection of the specific grade of retinopathy.

Assessment of colour vision as a screening test for sight threatening diabetic retinopathy before loss of vision.

AIM: To assess the effects of sight threatening diabetic retinopathy (STDR) on colour vision and to evaluate automated tritan contrast threshold (TCT) testing for STDR screening before significant visual loss. METHOD: Patients were recruited from a hospital based photographic screening clinic. All subjects underwent best corrected Snellen visual acuity (BCVA) and those with 20/30 vision or worse were excluded. Automated TCT was performed with a computer controlled, cathode ray tube based technique. The system produced a series of sinusoidal, standardised equiluminant chromatic gratings along a tritan confusion axis. Grading of diabetic retinopathy was made by one of the team of experienced ophthalmic registrars (SpR) using slit lamp biomicroscopy and a 78D lens; HbA(1c) and urine albumin were also tested. RESULTS: Patients with STDR had significantly worse TCT despite normal BCVA (p<0.0001). TCT yielded a sensitivity of 100% for detecting diabetic maculopathy and 94% for STDR with a specificity of 95%. Logistic regression analyses showed that TCT (p<0.001) and HbA(1c) (p<0.05) correlated significantly with the presence of STDR but duration of diabetes, urine albumin counts, and BCVA failed to show any significant correlation. No associations between TCT and duration of disease, TCT and HbA(1c), and TCT and urine albumin counts were found. CONCLUSION: Tritan colour vision deficiency was observed in patients with STDR despite their normal BCVA. These results indicate that automated TCT assessment is an effective and clinically viable technique for detecting STDR, particularly diabetic maculopathy, before visual loss.

Entonox as an analgesic agent during panretinal photocoagulation.

BACKGROUND/AIMS: Panretinal photocoagulation (PRP) reduces the risk of visual loss in proliferative diabetic retinopathy but some patients cannot tolerate PRP because of pain. Inhaled Entonox was evaluated as an analgesic during PRP. METHODS: A randomised, crossover, double masked pilot study was performed. Patients inhaled either air or Entonox and half the PRP was applied. The treatment was completed with the alternate inhaled gas. Patients graded pain experienced during both stages of the treatment using a visual analogue scale. Pain scores were compared using a paired t test. RESULTS: 20 patients participated. Mean pain scores from the Entonox and air treatments were 2.94 (SD 2.73) versus 3.73 (SD 3.20) respectively (p<0.03). CONCLUSION: Entonox can be used as a safe and effective analgesic agent during PRP treatment.