Many patients report subjective changes in vision following trabeculectomy. In a prospective study of 16 eyes, we have tried to determine the causes of these visual changes. Ninety-four per cent of eyes showed a change in uncorrected Snellen acuity 1 week following surgery. This change was due to a myopic shift in refraction secondary to changes in the anterior chamber depth. A 1 mm change in anterior chamber depth results in approximately a 2 dioptre change in refractive sphere. Visual acuity starts to return to pre-operative levels by the third post-operative week, from which point no eyes showed a deterioration in corrected acuity of more than one line of Snellen. The vertical corneal radius of curvature is reduced in the early post-operative period and there is a with-the-rule change in corneal astigmatism. This resolves over longer follow-up and the possible causes of this are discussed. No changes were noted in corneal thickness and there was no evidence of macular oedema over the follow-up period. Patients should be warned of these possible visual changes pre-operatively as many will have normal acuity prior to surgery.

Apraclonidine and pilocarpine have been shown to be effective in reducing the incidence of intraocular pressure (IOP) spikes following argon laser trabeculoplasty. An additional reduction in the incidence of acute pressure rise might theoretically be expected by combining these two effective agents. In a prospective randomised study we compared the ability of apraclonidine and pilocarpine alone and in combination to prevent post laser pressure spikes. Patients receiving regular pilocarpine to either eye were excluded. Seventy five eyes received either apraclonidine (26 eyes), pilocarpine (23 eyes), or both drugs (26 eyes). Apraclonidine 1% was instifflled 1 hour before and immediately after, and pilocarpine 4% immediately after trabeculoplasty. IOP was measured before and at 1, 2, and 3 hours following trabeculoplasty. In only two (8%) -eyes receiving combined treatment was a pressure rise observed. This frequency was significantly lower than that seen in eyes treated with apraclonidine alone (38%), or pilocarpine alone (39%). The mean fall in IOP at 1, 2, and 3 hours was significantly greater in those eyes receiving combined treatment than in the other two groups. (BrJ Ophthalmol 1994; 78: 30-32)

BackgroundThis study aimed to determine the impact of switching patients requiring multiple drug treatment from the dorzolamide-timolol fixed combination to the brinzolamide-timolol fixed combination and potential effects on tolerability and compliance.MethodsPatients were switched from dorzolamide-timolol to brinzolamide-timolol and questioned within a period of 4–26 weeks. Questions were asked to confirm if a specific side effect had been experienced, and then a numerical comparison between the two types of eye drop was made.ResultsThirty-one consecutive patients (12 males and 19 females aged 41–89 years) successfully completed the questionnaire. Comparison of the severity and chronicity of the side effects of the two types of fixed-combination eye drops showed that brinzolamide-timolol caused significantly less stinging for a shorter amount of time than dorzolamide-timolol; it also produced less eye redness for a significantly shorter amount of time. Brinzolamide-timolol produced more blurring, although the length of time this was present was similar to that for dorzolamide-timolol. No differences between the two eye drops were found for taste, overall impression, and likelihood of compliance.ConclusionOur study confirms the findings of other researchers pertaining to the side effect profile of brinzolamide-timolol after switching from dorzolamide-timolol, which is a reduction in stinging but an increase in blurred vision. The advantage of one eye drop over the other then becomes patient-specific, depending on which side effect they find most tolerable. We suggest that both eye drops are acceptable choices in treating patients with glaucoma, and are interchangeable if compliance becomes an issue because of a specific side effect of one eye drop or the other.

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Use of a modified Delphi approach has provided consensus agreement for the standards required for the development of virtual clinics to monitor glaucoma in the UK. It is anticipated that this document will be useful as a guide for those implementing this model of service delivery.