Asunto(s)

RESUMEN

PURPOSE: Two-colour computerised perimetry is a technique developed for assessing cone- and rod-function at fixed background luminances in retinal disease. However, the state of adaptation during testing is unknown but crucial in the interpretation of results. We therefore aimed to determine the adaptational state of rod- and cone-mechanisms in two-colour perimetry. METHODS: Sensitivity to 480 nm (blue) and 640 nm (red) Goldmann size V targets was determined for 10 normal subjects aged 16 to 46 years at 17 locations in the central 60 degrees of the visual field under scotopic conditions and then from -1.5 log cd m-2 to 2 log cd m-2 (white background) in 0.5 log unit steps. Data were fitted with threshold versus intensity (tvi) functions of the form logT = logT0 + log ((A + A0 )/A0 )n . RESULTS: No clear rod-cone break was observed for 640 nm stimuli. For 480 nm stimuli, transition from rod-detection to cone-detection occurred at mesopic illumination levels, where rod adaptation approached Weber behaviour. Cone detection mechanisms did not display Weber-like adaptation until the background luminance approached 1 log cd.m-2 . Diseases resulting in a "filter effect" - including disorders of the photoreceptors - are therefore predicted to affect sensitivity when rod function is probed with short-wavelength targets under scotopic conditions, but less so under mesopic conditions. Filter effects are similarly anticipated to affect cone function measured using long-wavelength targets under mesopic conditions (e.g., during microperimetry), but less so under photopic conditions. CONCLUSIONS: Asymmetries in adaptation in automated two-colour perimetry are predicted to artefactually favour the detection of losses in rod sensitivity under scotopic conditions and cones under mesopic conditions.

Asunto(s)

Asunto(s)

RESUMEN

AIMS: To investigate associations between socioeconomic status, retinal detachment type and post-operative visual outcomes in southern New Zealand.  METHODS: A retrospective review of all cases of rhegmatogenous retinal detachments in Dunedin Hospital over two years was performed. Patient demographics and macula involvement at presentation were the primary outcome measures. The New Zealand Deprivation Index was used to group patients into low (30% least deprived), medium (middle 40%) and high (30% most deprived). Patients were excluded if they were not from New Zealand, or had traumatic detachments.  RESULTS: During the study period, 95 retinal detachments in 94 patients were managed in Dunedin Hospital. Only 15% of retinal detachments occurred in the most deprived. More deprived patients had longer delays before assessment in hospital (mean of 29.8 days versus 10.1 days for the least deprived and 12.8 days for the medium category, overall p=0.025). There was no evidence of an association between deprivation and macula-off status (overall p=0.650) or visual acuity at one or three months (p=0.063 and p=0.328 respectively). Nor was there an association between referral pathway and macula-off status (p=0.242). CONCLUSIONS: Retinal detachment in southern New Zealand may be less common amongst those with the most deprived socioeconomic status who also experience longer delays till first treatment; but there was no association between socioeconomic status and patients being macula-off at presentation, or having poorer visual outcomes. More targeted patient education towards our most deprived citizens may reduce delays in treatment, and result in better visual outcomes.

Asunto(s)

RESUMEN

AIM: To determine the likelihood of progression from M3 grade maculopathy, and therefore the safety of these patients remaining under the care of a primary screener. METHODS: Patients graded M3 at diabetic screening were selected from the Wellington screening database. Photographs for this visit and the subsequent visit were obtained, and graded by a consultant ophthalmologist. Photographs graded M3 were included and progression of maculopathy between visits, number of patients with a reduction in vision and duration between visits were determined. RESULTS: Mean duration between visits for all patients was 255 (plus or minus 59.5) days. Of the 54 eyes studied, 15 or 33.3% progressed to M4 maculopathy at the subsequent visit. Despite progressing from M3 to M4, none had a reduction of vision by more than one line of Snellen acuity at follow up due to diabetic maculopathy. CONCLUSIONS: Rates of progression of maculopathy from M3 to M4 were of clinical significance. Despite this none had worsening visual acuity due to diabetic eye disease. This suggests patients with M3 maculopathy could be maintained under a primary screening programme, as is the case in the United Kingdom.

Asunto(s)

RESUMEN

To determine if primary selective laser trabeculoplasty (SLT) can be repeated with clinical benefit in patients with primary open-angle glaucoma (POAG). Forty-two eyes of 42 patients with POAG were studied. All patients underwent primary SLT treatment of 40-50 shots to the trabecular meshwork over 360°. The treatment response at the initial post-SLT visit (4 weeks), and second post-SLT visit (mean 4 months), clinical success and duration of clinical success were measured. SLT was repeated in all patients after failure to maintain target intraocular pressure (IOP). The same parameters were measured after repeat SLT. The main outcome measures were success of treatment (as defined by reduction of IOP by at least 20 % and below an individually determined target pressure), duration of treatment success and reduction in IOP. No significant difference between initial and repeat treatments was found for mean reduction in IOP or success rate, or duration of success. Survival analysis found significantly longer benefit for repeat treatment compared to initial treatment (P < 0.01). Repeat SLT treatment in eyes with POAG has similar efficacy to primary SLT treatment with respect to reduction in IOP and success rates, produces a longer duration of treatment success.

Asunto(s)

RESUMEN

Self-diagnosis has been around for many years. In today's society with free access to information, particularly through the Internet, it is more prominent than ever. With new information sources available to patients, doctors may have their diagnostic process influenced. This is the case of a gentleman who self-diagnosed, and subsequently influenced his doctor's diagnostic process, with results detrimental to his outcome. It illustrates the importance of awareness of the risks of self diagnosis, and management of patients who present with information and preconceived ideas regarding their condition.

Asunto(s)