Biomedical subjects
S J Tuft
Publications and source records attributed to S J Tuft.
Fusarium solani keratitis following LASIK for myopia.
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Corneoscleral fibrous histiocytoma.
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Early decentration of plate-haptic silicone intraocular lenses.
We report 4 eyes of a consecutive series of 1299 that developed early decentration of a 10.5 mm diameter plate-haptic silicone intraocular lens (IOL) after uneventful phacoemulsification. All eyes had an intact continuous curvilinear capsulorhexis (CCC) with the IOL placed in the capsular bag. After an initial period of good vision, patients noted the onset of glare or monocular diplopia between 1 and 5 weeks after surgery. On examination, there was no significant anterior capsule contraction; however, the edge of the IOL optic was visible in the undilated pupil. There was adhesion between the anterior and posterior capsules at the margin of the CCC that maintained the IOL decentration. Decentration recurred in 1 eye after the IOL was rotated 90 degrees and recentered. Symptoms resolved in 3 eyes after the IOL was removed and replaced with a rigid IOL with a larger diameter optic.
Systemic cyclosporin A in high risk penetrating keratoplasties: a case-control study.
AIM: To examine the efficacy of systemic cyclosporin A (CSA) in preventing rejection and graft failure in high risk keratoplasty (PK). METHODS: A retrospective case-control study with 49 patients in both the CSA group and the control group. The patients receiving CSA were at high risk of graft rejection and failure. Controls were identified from surgical audit books and had high risk characteristics. RESULTS: There was no statistical difference in preoperative risk factors and the use of postoperative topical steroids between the two groups. The median follow up in the CSA group was 22 months and 27 months in the control group. One or more rejection episodes occurred in 18 out of 49 (36.7%) cases in the CSA group and 26 out of 49 (53.1%) in the control group. Graft failure from all causes occurred in 16 (32.7%) CSA patients and 18 (36.7%) control patients. Four (8.2%) of the CSA group compared to eight (16.3%) in the control group failed because of rejection. 22 (44.9%) out of 49 patients in the CSA group had side effects. In five (10.2%) patients, CSA was stopped because of the side effects; eight patients had elevated serum urea and creatinine and four developed hypertension. Minor side effects reported include gum hyperplasia, increased sweating, backache, nausea, feeling unwell, oral candidiasis, cramps, and paraesthesia of the extremities. CONCLUSION: These results suggest that the benefit of CSA over conventional therapy in preventing rejection episodes and subsequent graft failure is only moderate and did not reach statistically significant levels in this study. Considering the high frequency of side effects and the cost of CSA, a randomised control trial may be necessary to determine the true value of CSA in high risk penetrating keratoplasty.
Outcome of cataract surgery in patients with retinitis pigmentosa.
AIM: To determine the visual benefit of cataract extraction in patients with retinitis pigmentosa and to identify risk factors for poor outcome. METHODS: A retrospective analysis was undertaken of a continuous series of 142 eyes of 89 patients with retinitis pigmentosa undergoing cataract surgery between 1985 and 1997. RESULTS: Mean age at surgery was 47.5 years (range 24-81 years). In 100 eyes there was posterior subcapsular lens opacity alone, 37 eyes also had moderate nuclear sclerosis, and five had only nuclear sclerosis. All patients had central visual fields of <10 degrees. Overall, mean visual acuity improved from 1.05 (SD 0.38) preoperatively to 0.63 (SD 0.49) postoperatively on the logMAR scale. Significant postoperative capsular opacification occurred in 88/139 eyes (63%) and 45.1% required capsulotomy. Anterior capsulotomy was undertaken in 5/52 (9.6%) eyes undergoing phacoemulsification. Postoperative macular oedema was noted in 20 (14%) eyes. Visual acuity improved in 109 eyes (77%), was unchanged in 29 eyes (20.5%), and worsened after surgery in four eyes (2.5%). 86/89 patients reported major improvement of visual function. CONCLUSIONS: Cataract surgery for relatively minor lens opacities is beneficial in patients with retinitis pigmentosa, and most report subjective improvement of visual symptoms. The incidence of capsular opacification is high and anterior capsular contraction may occur. The number of eyes with poor vision due to macular oedema was unexpectedly low.
Effect of age on visual outcome following cataract extraction.
AIM: To determine the effect of age on final corrected visual acuity following cataract extraction. METHODS: A case series of 880 patients aged 60 years and older undergoing cataract extraction between 1996 and 1999 was studied. The best corrected visual acuity was assessed at discharge from the service and the proportion of patients who achieved a postoperative acuity of > or = 6/12 was determined for different age groups. Analysis was also performed after exclusion of patients identified preoperatively as having ocular comorbidity that was thought to limit their final corrected acuity. The odds ratios for visual outcome were calculated for age using multiple logistic regression analysis to adjust for other prognostic factors. RESULTS: A significant age effect was observed, with the proportion of patients who had no ocular comorbidity identified preoperatively and who achieved a visual acuity of > or = 6/12 at discharge decreasing with age (p<0.001). In patients with no comorbidity the odds of achieving an acuity of > or = 6/12 were 4.6 times higher in the 60-69 year age group than in the oldest age group (80+ years). CONCLUSIONS: Age is a significant determinant of visual outcome. This has implications if a points system incorporating an assessment of visual acuity or if visual acuity alone is used to determine the threshold for eligibility for cataract surgery.
In vitro antibiotic resistance in bacterial keratitis in London.
AIM: To document changes in the profile of bacterial isolates from cases of keratitis and changes in their susceptibility to first line antibiotic therapies. METHODS: A retrospective review was performed of all bacterial isolates from cases of keratitis seen between 1984 and 1999. In vitro laboratory susceptibilities to antibiotics were determined by the Kirby-Bauer disc diffusion method. The number of isolates, changes in the proportion of bacterial types, and the number that were fully resistant to monotherapy (ofloxacin), dual therapy (gentamicin and cefuroxime), and prophylactic treatment (chloramphenicol) were calculated. RESULTS: There were 1312 bacterial isolates over 16 years. Gram positive bacteria accounted for 54.7% of isolates and Staphylococcus species (33.4%) were the most frequently isolated organisms. During the study period there has been an increase in the proportion of Pseudomonas species isolates but no overall increase in the proportion of Gram negative isolates. There has not been an increase in the proportion of isolates resistant to ofloxacin since 1995 or an increase in resistance to the combination of gentamicin and cefuroxime. However, since 1984 there has been a significant increase in proportion of Gram negative organisms resistant to chloramphenicol (p=0.0019). CONCLUSIONS: An increase in the in vitro resistance of organisms to first line therapies for bacterial keratitis has not been observed. An increased resistance to chloramphenicol indicates that this drug is unlikely to provide prophylactic cover when Gram negative infection is a risk. Continued monitoring for the emergence of antibiotic resistance is recommended.
Assessment of the effect of oral clarithromycin on visual outcome following presumed bacterial endophthalmitis.
PURPOSE: The use of clarithromycin was assessed as a biofilm reducing agent in the management of bacterial endophthalmitis. METHODS: 84 eyes of 83 patients presenting with clinical signs highly suggestive of bacterial endophthalmitis were treated using a standard regimen of intraocular vancomycin, amikacin and systemic steroids, which in addition included oral clarithromycin. Ocular penetration of oral clarithromycin in healthy and inflamed eyes was also assessed. RESULTS: Comparing visual acuities at presentation and 6 months, 66% of patients demonstrated an improvement. Intraocular samples were culture positive in 58% of eyes. As compared to culture positive cases, more culture negative cases achieved a visual acuity of 6/12 or better (p = 0.0047). As compared to patients receiving the standard protocol but without clarithromycin, a greater number of culture negative cases demonstrated an improvement in vision of > or = + 6 Snellen lines (p = 0.023). The ocular penetration of clarithromycin into the anterior chamber of inflamed eyes appears sufficient to allow anti-biofilm activity against bacteria at the basic pH encountered in eyes with endophthalmitis. CONCLUSIONS: The ocular penetration of clarithromycin appears adequate for anti-biofilm activity in inflamed eyes. The beneficial effects of oral clarithromycin on visual outcome has been demonstrated in culture negative eyes with clinical signs highly suggestive of bacterial endophthalmitis. The final visual outcome for culture positive cases remains poor.
Delayed dislocation of foldable plate-haptic silicone lenses after Nd:YAG laser anterior capsulotomy.
PURPOSE: To report two eyes (two patients) that had plate haptic silicone intraocular lenses that dislocated 4 weeks after Nd:YAG laser anterior capsulotomy to relieve capsular contraction. METHODS: Case reports. The clinical records of two patients were reviewed. RESULTS: After uncomplicated phacoemulsification with implantation of plate haptic silicone lenses in the capsular bag, two eyes of two patients developed visually notable early contraction of the capsulorhexis. Three radial-relieving incisions approximately 1 mm long were made with a Nd:YAG laser in each eye to enlarge the capsulotomy. Although vision improved, both patients experienced sudden further reduction of vision after approximately 4 weeks. Upon examination of both patients, we noted an extension of an anterior radial capsulotomy incision peripherally, and the intraocular lenses had dislocated from the capsular bag into the ciliary sulcus. CONCLUSIONS: Tears may extend after radial-relieving incisions have been used to enlarge a contracted anterior capsulotomy, possibly because of continued capsular fibrosis. This may allow extrusion of a foldable intraocular lens from the capsular bag.
Limbal vernal keratoconjunctivitis in the tropics.
OBJECTIVE: This study aimed to describe the pathology of vernal keratoconjunctivitis (VKC) in children from Kenya. DESIGN: Case series. PARTICIPANTS: Ten patients with clinically active and untreated limbal VKC and five age-matched control subjects without external eye disease were recruited from a district eye hospital in Kenya. MAIN OUTCOME MEASURES: Paraffin sections of limbal and tarsal conjunctiva were examined by tinctorial and immunocytochemical methods to characterize the inflammatory infiltrate. RESULTS: In comparison with control subjects, patients with VKC were more likely to show squamous metaplasia of the tarsal conjunctiva. The patients with VKC had cellular infiltration of both the stroma and epithelium consistent with chronic inflammation, particularly in the biopsy specimens taken from the limbus. In tarsal conjunctiva, the stromal infiltrate consisted of a diffuse T-lymphocyte reaction with clustering of B-lymphocytes; mast cells, immunoglobulin E (IgE) plasma cells, and eosinophils also were prominent. Mast cells and eosinophils were found within the epithelium in the more severely inflamed biopsy specimens. CONCLUSIONS: These features are similar to those in reports of VKC in temperate regions, although the degree of B-lymphocyte clustering is greater in tropical patients with VKC. Although none of the patients had other symptoms of atopy, the authors findings are consistent with those for an allergic basis for this disease.
Acute microcystic corneal epitheliopathy after daily soft contact lens wear.
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Aging and the cornea.
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Corneal infiltration after recurrent corneal epithelial erosion.
AIMS: To describe the clinical features of patients with a history of recurrent corneal epithelial erosion who develop acute corneal infiltration. METHODS: The records were reviewed of patients who had previously been examined and treated for recurrent corneal epithelial erosion and who presented again with signs suggestive of a microbial keratitis. RESULTS: 11 patients were described; one patient presented with similar signs on two occasions. There was typically a paracentral epithelial defect > 2 mm in diameter with an associated stromal infiltrate and an intense anterior uveitis. Three patients had a hypopyon, and four developed a subepithelial ring infiltrate. Samples were taken for microscopy and bacterial culture, with a positive isolate from two of 12 episodes (16%). Treatment with topical antibiotics and topical corticosteroid resulted in rapid re-epithelialisation and a reduction of inflammation. There was good visual outcome for all eyes, with a recurrence or symptoms of epithelial erosion in only one eye after a mean follow up period of 18 months. CONCLUSIONS: Corneal infiltrates are an uncommon complication of recurrent corneal epithelial erosion. Despite the intensity of the infiltration the majority are culture negative using established techniques. There is typically rapid resolution and a good visual outcome, with a tendency for the episode to mark the end of further symptoms of epithelial erosion.
A histochemical and x-ray diffraction study of keratoconus epikeratoplasty. Report of two cases.
Two epikeratoplasty lenticules (Epi-L) with keratoconus host corneas (Epi-H) were removed by penetrating keratoplasty because of poor visual acuity although they were clinically clear. Light microscopy showed that the keratocytes were underpopulated and unevenly distributed in Epi-L. Transmission electron microscopy showed that abnormal sized proteoglycans (PGs) were unevenly accumulated in the stromas of both Epi-L and Epi-H. The low-angle x-ray diffraction results from case 1 showed lower collagen interfibrillar spacings, compared with those from one keratoconus cornea, seven cryolenticules, and four normal human corneas. The fibril diameters and the collagen axial periodicity D were similar in all tissues. Allowing selected samples to swell, the interfibrillar spacing increased by 30.6-45.5% in Epi-H and by 29.8% in the keratoconus control. However, it increased by only 7.6-9.7% in Epi-L and by 11.4% in a cryolenticule. The uneven distribution of PGs and the lower interfibrillar spacings in the swollen lenticules suggest that there is an uneven distribution of water in different parts of the Epi-L and Epi-H stromas. This may lead to a variation of the refractive index or optical properties in the stroma and the deterioration of the visual image, which may explain the poor visual results.
Comparative intraocular penetration of topical and injected cefuroxime.
AIMS: The choice of a prophylactic antibiotic for cataract surgery is dependent on its antibacterial activity and tissue penetration. The influence of the route and timing of administration of cefuroxime on its intraocular concentrations was examined. METHODS: 120 patients were recruited before cataract surgery into a prospective trial to compare the anterior chamber concentration of cefuroxime at a fixed time after administration by three routes. In a further 110 patients, the interval before sampling was varied in order to permit an examination of the kinetics of penetration. In another 10 patients, cefuroxime was given topically at the completion of surgery to assess the effect of a corneal wound on aqueous penetration. Cefuroxime concentrations were measured by high performance liquid chromatography on 0.2 ml samples of aqueous aspirated from the anterior chamber. Mean aqueous concentrations of cefuroxime for each group were compared using Student's t test. RESULTS: After 25 mg cefuroxime, mean aqueous concentrations increased in the order forniceal (< 0.1 microgram/ml) < topical (0.18 microgram/ml) < subconjunctival (2.31 microgram/ml) when sampled 12-24 minutes after administration. Aqueous concentrations of cefuroxime reached a peak between 80 and 110 minutes after both forniceal and peribulbar injection but were still rising at this time after subconjunctival injection. Topical application of 12.5 mg cefuroxime to eyes with a 10 mm corneal wound resulted in a mean aqueous concentration of 9.34 micrograms/ml. CONCLUSION: In the intact eye, only sub-conjunctival injection resulted in clinically significant aqueous concentrations of cefuroxime (> 1 microgram/ml) between 12 and 24 minutes after administration. For all routes, maximal aqueous concentrations were delayed by at least 80 minutes from administration. In the presence of a corneal wound, high aqueous levels of cefuroxime were rapidly attained after topical application.
Bilateral penetrating keratoplasty for keratoconus.
PURPOSE: To determine the effect of bilateral surgery on the rejection-free survival of penetrating keratoplasties (PK) performed for keratoconus. METHODS: The records of 587 patients with a PK for keratoconus who attended a single center over a 7-year period were reviewed. Details on 400 patients were sufficiently complete to permit a multivariate analysis of the factors suspected to influence graft survival. In 165 of these patients with bilateral grafts, the effect of a contralateral PK on graft survival was evaluated using actuarial methods. RESULTS: In first grafts for all patients, there was an increased rate of graft rejection with a host trephine greater than 7.50 mm in diameter and in patients with severe allergic eye disease (P < 0.01). In patients who had bilateral grafts, a graft to the contralateral eye increased the risk of rejection in the first eye to be grafted, and although this effect reduced with time, it was still present after an interval of up to 6 years between surgeries. A rejection episode in the first eye to be grafted increased the risk of rejection in the second eye (P < 0.001), but overall the second eye had a significantly lower risk of rejection when compared with either the first grafted eye or unilaterally grafted eyes (P < 0.001). The risk to the second grafted eye further reduced as the interval between the surgeries increased. CONCLUSIONS: In keratoconus, the diameter of the host trephine, severe allergic eye disease, and a graft surgery to the contralateral eye determine the risk of rejection in the index eye. The reasons the second grafted eye of patients receiving bilateral PKs appears to have an enhanced rejection-free survival are discussed.
Long-term refraction and keratometry after penetrating keratoplasty for keratoconus.
We looked for continued corneal ectasia after penetrating keratoplasty (PK) for keratoconus by measuring long-term changes in keratometry and refraction after final suture removal. The records of 587 patients who had had PK for keratoconus and who had attended a single center over a 7-year period were examined. For 184 eyes keratometry or refraction data were available from the first operated eye from the 6-month interval after final suture removal, and, in these patients, these readings were repeated as they continued to be seen for review. The changes in mean keratometry, spherical equivalent, and cylinder over the period of follow-up were then calculated, and these data were assessed by regression analysis. We found no significant change with time in the amount of cylinder when measured by either refraction or keratometry. There was a trend (p = 0.075) toward an increase in the mean keratometry with time, suggesting a gradual flattening of the cornea, and there was a clinically small, but statistically significant (p < 0.001), time-dependent increase in the residual myopia in the years after final suture removal. In conclusion, we found a wide range in the individual values for changes in keratometry or refraction in the years after suture removal following PK for keratoconus but no evidence overall to suggest continued corneal ectasia or a recurrence of keratoconus in these grafts.