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Biomedical subjects

S Longstaff

Publications and source records attributed to S Longstaff.

17 recordsLinked to original sources

Influence of apraclonidine and pilocarpine alone and in combination on post laser trabeculoplasty pressure rise.

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 instilled 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.

Adrenergic beta-Agonists↗

Intra-operative use of 5-fluorouracil in glaucoma filtering surgery.

This study reviews the outcome of 14 eyes considered to be at risk of surgical failure undergoing trabeculectomy with 5-Fluorouracil (5-FU). The antimetabolite was administered intra-operatively by placing a surgical sponge soaked in 5-FU (25 mg/ml) directly on the sclera under the conjunctival flap for 5 minutes. All eyes showed a reduction in intraocular pressure (IOP) at a mean follow-up of 18.5 weeks, and only one eye required topical antiglaucoma medication. Mean IOP reduction at final follow-up was 43.1%. No eyes showed any corneal problems associated with the intra-operative use of 5-FU. These results suggest that the intra-operative use of 5-Fluorouracil is an effective way of improving surgical success in at risk eyes. The early complications appear to be less than those associated with post-operative subconjunctival injections of 5-FU, but the long-term differences are still to be shown.

Adult↗

A prospective study examining the changes in factors that affect visual acuity following trabeculectomy.

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.

Aged↗

Prevention of acute postoperative pressure rises in glaucoma patients undergoing cataract extraction with posterior chamber lens implant.

Acute elevations in intraocular pressure (IOP) commonly follow extracapsular cataract extraction and lens implant in glaucoma patients. Thirty six patients with glaucoma undergoing cataract extraction and posterior chamber lens implantation received one of three treatments. Group 1: 500 mg of Diamox Sustets (acetazolamide) 1 hour preoperatively (10 patients); Group 2: peroperative intracameral Miochol (acetylcholine) (11 patients); Group 3: the above treatments combined (15 patients). IOPs were measured at 3, 6, 9, and 24 hours postoperatively. The average of the maximum pressure rises above the preoperative level over the 24 hour period was greatest for the group receiving acetazolamide only at 8.9 mm Hg; for the acetylcholine group the average maximum rise was 6.3 mm Hg; while the combined treatment group showed a decrease of 0.7 mm Hg. IOP rises of > 6 mm Hg were seen in 7% of patients (one of 15) in the combined treatment group, 45% (five of 11) of the acetylcholine group, and 70% (seven of 10) of the acetazolamide group. IOP rises of > 10 mm Hg were seen in 7% of the combined treatment group, in 18% of the acetylcholine only group, and in 50% of the acetazolamide only group. A pressure rise > 20 mm Hg was seen in one patient receiving acetazolamide only and one patient receiving acetylcholine only. The difference between the acetylcholine group and the combined group for rises > 6 mm Hg was significant using the chi 2 test while the acetazolamide group showed a significant difference for rises > 6 and 10 mm Hg compared with the combined group. All acute pressure rises were recorded before or at 9 hours following operation except in the combined treatment patient where the rise occurred at 24 hours. To prevent the acute IOP rises seen following cataract surgery with lens implant in glaucoma patients we recommend combined ocular hypotensive therapy.

Acetazolamide↗

Genetic counselling for myotonic dystrophy: a comparison of lens examination and DNA linkage studies.

Genetic counselling in presymptomatic individuals with a family history of myotonic dystrophy (DM) is problematic. A genetic test to identify the presymptomatic carrier of the gene for DM would therefore be advantageous. We report studies comparing ophthalmic examination with a genetic test based on DNA linkage studies in nine DM families. The genetic test involved the use of five probes from four loci linked to the DM locus. Some discrepancies between ophthalmic and genetic tests were observed. Genetic counselling following prediction of genetic status was possible for 18 out of 20 patients from seven out of nine families.

Adolescent↗

Topical timolol and serum lipoproteins.

Oral timolol taken for the treatment of systemic hypertension has been shown to affect adversely serum lipoprotein levels. In a 15-week study on 19 patients topical timolol therapy for raised intraocular pressure was found to have no significant adverse effect on serum lipoprotein levels. This is reassuring in view of the large number of patients on this form of long term therapy, and selection of the type of beta blocker to use should not be influenced by lipid changes associated with the oral form of the drug.

Administration, Topical↗

Glaucoma triple procedures: efficacy of intraocular pressure control and visual outcome.

Sixty-three glaucoma triple surgeries [combined trabeculectomy, extracapsular cataract extraction (ECCE), and posterior-chamber intraocular lens (PC-IOL) implantation] were reviewed. Intraocular pressure (IOP) was controlled satisfactorily in all cases; 25% required additional glaucoma therapy but fewer glaucoma medications. Eighty-six percent achieved 6/12 or better visual acuity. Postoperative IOP and visual acuity results were similar to those achieved by trabeculectomy or ECCE/PC-IOL, respectively. Cumulative years of preoperative glaucoma therapy had an adverse effect on postoperative IOP control.

Aged↗

A controlled study of the ocular effects of tamoxifen in conventional dosage in the treatment of breast carcinoma.

The use of tamoxifen is expanding in its application in the treatment of breast carcinoma, and proposed prophylactic use. Tamoxifen in high dosage and in some reports at conventional dosage is associated with ocular toxicity. This study in a single blind fashion examined 79 patients receiving tamoxifen for varying treatment durations at conventional dosage and 115 patients not receiving tamoxifen. No ocular toxicity was found. Further follow up studies are required to ensure no toxicity develops in patients receiving high cumulative dosage on conventional therapy.

Aged↗

Retinal break formation following contrecoup trauma: case report.

A previously healthy 38-year-old woman was involved in a road traffic accident resulting in severe commotio retinae. Subsequently extramacular retinal dissolution was noted (not previously described). The patient was treated by closed intraocular microsurgery with a successful anatomical and functional result.

Adult↗

Factors affecting intraocular lens power calculation.

Intraocular lens power calculation is increasing in use in the United Kingdom. Primarily to avoid anisometropia, intraocular lens power calculation may also be used to provide the patient with three rather than two working distances, but to achieve this greater accuracy of IOL power calculation is required. Using the SRK regression formula, three groups of patients have been studied. The effect of inaccurate use of the formula of choice is shown and the need to modify the 'A' constant to account for variation both in technique and biometry equipment emphasised. The variation in results due to inaccurate biometry are statistically assessed. Accuracy of IOL power calculation requires consistency but not absolute accuracy in biometry. No ocular factors were found to affect the accuracy of IOL power calculation.

Anthropometry↗