V. Lozano López

Topographical spatial summation in glaucoma

PURPOSE Stimulus luminance (L) and area (A) are related by the equation LxAk=constant. The authors evaluated the k value at 66 positions of the central visual field in patients with glaucoma, to modify L and A simultaneously in order to examine advanced glaucomas with a bigger dynamic range. METHODS The luminance limitation of a computer screen with automatic photometric control was compensated for by increasing the stimulus area in the range between 0 and 17 dB, using the k topographic values previously calculated on normal subjects. Four initial series of 21, 12, 10, and 10 glaucomas were sequentially examined with the Octopus 311 in which the stimulus size cannot be freely changed during the examination, and with the experimental method (Pulsar-SAP) modifying stimulus sizes to equal the results. k Final estimation was verified in 60 new cases. RESULTS k Values increase progressively with defect deepness. Values higher than those of the normal population with equivalent topographic differences were obtained. Correlation between indices was as follows: MD: r=0.94 (p<0.0001); square root of the loss of variance (sLV): r=0.93 (p<0.0001). Frequency of local defects was similar in both procedures. Average topographic differences between thresholds were usually less than 1 dB. The average threshold difference favored Pulsar-SAP by 0.45 dB at those points where the average threshold of both examinations was less than 18 dB and 0.37 dB where such average was higher than or equal to 18 dB. CONCLUSIONS k Value is higher in patients with glaucoma than in normal subjects, although the topographic features are similar. It is feasible to design a scale combining stimulus luminance and sizes to use screens with relative low brightness as surfaces for visual field examination.

Resultados coste-efectividad del implante de dexametasona en edema macular

OBJECTIVE To analyze the cost-effectiveness and benefits of a dexamethasone intravitreal implant (Ozurdex®, Allergan, Irvine, CA, USA.) in its clinically relevant applications. MATERIAL AND METHODS A total of 88 eyes of 86 patients with macular edema of > 300 μm measured by optical coherence tomography (Cirrus Zeiss, Dublin, CA, USA) were included in this two-year retrospective study, with a minimum of 6 months follow-up. The patients were divide into 3 groups: group 1 with macular edema in retinal vein occlusion, group 2 with non-infectious posterior uveitis, and group 3 with diabetic macular edema. The treatment was off-label but supported by the literature. Before implantation, and on days 1, 30, 60, 90 and 180, corrected visual acuity (Snellen), central retinal thickness, intraocular pressure and biomicroscopy were evaluated. The cost-benefit analysis was tabulated by line of visual acuity gained, comparing the main therapeutic alternatives and assessment of the safety profile of the dexamethasone intravitreal implant (Ozurdex®, Allergan, Irvine, CA, USA). RESULTS The results of this study did not differ from the published studies, in terms of visual acuity improvement in 63.3% of cases, and with central macular thickness improvement in 97% of cases. There were relapses, which occurred after 120 days on average, and the need for retreatment was 40.9%. Increased intraocular pressure >23 mm Hg was among the side effects in 29.54%, and was controlled with topical treatment, except in 1.13% requiring surgical treatment. The development of cataract was 44.7%, and 10.6% required surgery. Treatment results showed less frequent use of Ozurdex® than other treatments for disease control, being a cost saving option. DISCUSSION Cost-effectiveness analyses are clinically relevant when applying treatment strategies in patients with macular edema. Dexamethasone intravitreal implant appears to be a safe and efficient therapy.