Catatrac: a novel red light-emitting diode device for screening cataracts in the developing world.

BACKGROUND/AIMS: The purpose of this study was to critically evaluate the Catatrac device as a potential tool for rapid cataract screening in the developing world. METHODS: Patients attending the day case unit at Gartnavel General Hospital for routine cataract surgery were recruited into the study, and divided into two groups: those with mild cataracts with LogMAR acuities <0.48, and those with advanced cataracts with LogMAR acuities ≥0.48. The subjects were examined without pharmacological dilation in a dimly lit room independently by two nurses. Each patient was then examined by an ophthalmologist with a slit lamp, after dilation. If present, cataracts were graded objectively according to the LOCS III classification system. RESULTS: One hundred and twenty-two eyes of 73 patients were screened for the presence or absence of cataract using the Catatrac device. Thirty-nine eyes had mild cataracts, 43 eyes had advanced cataracts, and there were 40 control eyes with no cataracts. For detecting advanced cataracts, the two nurses using the Catatrac device had a specificity of 95.0%, a sensitivity between 86.0 and 93.0%, and κ values between 0.81 and 0.88 for agreement with slit lamp assessment. For detecting mild cataracts the two nurses using the Catatrac device again had a specificity of 95%, sensitivity of 71-84.6%, and κ values between 0.67 and 0.80 for agreement with slit lamp assessment. Interobserver agreement between the two nurses had a κ value of 0.61 for mild cataract and 0.74 for advanced cataract. CONCLUSION: The Catatrac device has a high specificity, sensitivity, and interobserver agreement for advanced cataracts. Although having a slightly lower sensitivity for mild cataracts, the authors believe that this study has demonstrated that it may be a low cost and easy to use device for rapid screening of visually significant cataracts in the developing world.

Transscleral diode laser cycloablation in patients with good vision.

PURPOSE: To investigate the effect of diode laser cyclophotocoagulation for glaucoma on central visual function in patients with good visual acuity (VA). PATIENTS AND METHODS: Patients with preoperative VA 20/60 or better who had undergone cyclodiode treatment according to a standard protocol were evaluated retrospectively. The primary outcome variable was a recorded loss of two or more Snellen lines of best corrected VA during follow-up. Successful intraocular pressure (IOP) control was defined as being between 6 and 21 mmHg inclusive without oral acetazolamide or other glaucoma surgery. RESULTS: 49 eyes of 43 patients with a median pretreatment acuity of 20/30 were included (range 20/16-20/60). After a mean duration of follow-up of 5.0 years, median VA was 20/60 with a line loss of two or more recorded in 15 eyes (30.6%) (mean survival time 7.7 years). 67.3% (33/49) retained VA 20/60 or better, but VA deteriorated by one Snellen line or more in 31 (63.2%), and in 16.3% (8/49), final VA was <20/200. In cases experiencing a two-line loss in acuity, the main causes were glaucoma progression (nine cases) and macula oedema (four cases). Visual loss was unrelated to total treatment dose (mean 99.7 J), initial acuity or initial IOP level. IOP was controlled at final follow-up in 39/49 (79.6%) with no cases of hypotony. CONCLUSIONS: Most of these eyes with difficult to manage glaucoma retained their good VA over long-term follow-up after undergoing diode laser cyclophotocoagulation. The proportion losing two Snellen lines is in line with that reported after trabeculectomy or tube surgery. These results suggest a possible role for the use of transscleral cyclodiode in selected eyes with significant visual potential. Further controlled prospective studies are required to better define this role.

Early bleb leak after trabeculectomy and prognosis for bleb failure.

AIM: To determine whether early bleb leak after MMC trabeculectomy affects intermediate intraocular pressure (IOP) outcome. METHODS: Retrospective case note review. All cases of MMC trabeculectomy with at least 1-year follow-up were included. Cases where a bleb leak occurred within the first month were identified. All cases without an early bleb leak formed the control group. Patient demographics and clinical factors were analysed to determine any factors predisposing to bleb leakage. IOPs were compared for 1 year postoperatively and final follow-up. RESULTS: A total of 119 trabeculectomies were included. Of these 27 (22.7%) had an early bleb leak. The remaining 92 cases formed the control group. Mean age of cases was 70.7 years. Mean follow-up time was 19.5 months. Mean time of detection of the bleb leak was 9 days (range 1-21 days). Four cases (14.8%) were managed by primary resuturing. Thirteen cases (48.1%) were managed conservatively with a bandage contact lens. Ten cases (37.0%) resolved with expectant management. There was no statistically significant difference between the two groups with regards to IOP measurement at any time point. Intervention rates were similar with regards to bleb massage, 5-fluorouracil injection, and needling revision. No factors were identified between the two groups that predisposed to bleb leaks occurring. CONCLUSION: Our data suggest that early bleb leak is not a poor prognostic indicator for intermediate bleb survival and IOP control in patients undergoing MMC trabeculectomy. No additional bleb manipulations compared with the control group were required to achieve a satisfactory IOP outcome.

Peripapillary retinal nerve fibre layer thickness in highly myopic Caucasians as measured by Stratus optical coherence tomography.

AIMS: To assess peripapillary retinal nerve fibre layer (RNFL) thickness distribution in a group of non-glaucomatous Caucasian subjects with a high degree of myopia and to evaluate the relationship between RNFL thickness, both global and sectoral, and other variables including axial length and optic disc size. METHOD: 31 eyes of 31 healthy Caucasian subjects with spherical equivalent >or=-6 dioptres (D) were recruited from a community optometric practice. RNFL thickness was measured using the Stratus optical coherence tomography (OCT) Fast RNFL 3.4 mm scan protocol. Optic disc area was measured using the Heidelberg Retinal Tomograph II and axial length using the IOL Master. Associations between RNFL measurements and axial length, spherical equivalent and optic disc area were evaluated by linear regression analysis. RESULTS: The sample had a mean age of 48.1 years, mean spherical equivalent of -7.7 D, and mean axial length of 26.5 mm. The mean (SD) RNFL thickness was 81.4 (13.7) microm. In comparison with the Status OCT normative database, the distribution of RNFL thickness was substantially lower in the study group. The greatest disparity was around 7 clock hours centred on the nasal meridian in which 26/31 (83.9%) had one or more clock hours in which RNFL thickness was below normal at the 5% probability level in comparison with the Stratus normative database. No statistically significant associations between mean RNFL thickness and age (p = 0.12), gender (p = 0.76), spherical equivalent (p = 0.80), cup:disc area ratio (p = 0.88), optic disc area (p = 0.14) or axial length (p = 0.18) were identified in this group. However, RNFL thickness from vertical quadrants and in particular the superior sector correlated strongly with axial length, age and optic disc area. CONCLUSIONS: The Stratus OCT normative database may be misleading in highly myopic eyes from Caucasians resulting in a substantial proportion of false positive errors. Particular caution is needed when the RNFL appears to be below the normative database normal limit at the upper or lower poles or on the nasal side of the disc. Stratified normal databases are required for accurate diagnosis of conditions resulting in nerve fibre loss such as chronic glaucoma.

Frequency of bleb manipulations after trabeculectomy surgery.

AIM: To quantify the type and frequency of postoperative bleb manipulations undertaken after modern glaucoma surgery. METHODS: Bleb manipulations were recorded after trabeculectomy surgery on 119 consecutive patients with at least 1 year of follow-up. The type of intervention and time after surgery were recorded. Statistical analysis identified success rates at various intraocular pressure (IOP) cut-off definitions and identified factors that increased the risk for bleb manipulation. RESULTS: In all, 78.2% of trabeculectomies were followed by some form of bleb manipulation. Almost 49% of blebs underwent massage and a similar number required at least one suture removal, 31.1% required at least one 5-fluorouracil (5-FU) injection and 25.2% required at least one needling and 5-FU injection. The median time to the first intervention for massage, suture removal, 5-FU injection, and needling and 5-FU injection were 1, 14, 14 and 43 days, respectively. IOP measurements were higher at all follow-up time points in the intervention group. Failure to achieve specific IOP target pressures was also generally poorer in the 5-FU, and needling and 5-FU intervention groups. CONCLUSIONS: Postoperative intervention is a frequent occurrence after modern glaucoma surgery. This requires intensive postoperative follow-up and is a labour-intensive undertaking. Despite interventions in our group of patients, IOP in the intervention group was always higher than in the group that required no intervention.

First day review after uncomplicated phacoemulsification: is it necessary?

PURPOSE: To determine whether first day follow-up is necessary after routine uncomplicated phacoemulsification cataract surgery. METHODS: Data collected prospectively at day 1 postoperative review. RESULTS: In 510 consecutive cases, serious complications occurred in 8 (1.6%) (wound leak [4], corneal abrasion [2], iris prolapse [1], hyphema [1]). Intraocular pressure (IOP) >30 mmHg was found in 26 (5.1%) and was strongly associated with a diagnosis of pre-existing glaucoma or ocular hypertension (odds ratio [OR] 7.7). Symptoms of headache or ocular discomfort occurred in 40 (7.8%), mostly in association with raised IOP, and were also associated with pre-existing glaucoma or ocular hypertension (OR 4.7). Central corneal edema was found in 61 (12.0%). In the absence of corneal edema, IOP was >30 mmHg in only two cases (0.39%). CONCLUSIONS: Few sight-threatening complications were detected on the morning after an uncomplicated procedure. First day follow-up may be safely omitted if adequate patient counseling is undertaken and there is provision of adequate access to eye services. Review prior to discharge on the day of surgery would provide an opportunity to detect these few surgical complications and for counseling. A diagnosis of glaucoma or ocular hypertension is a risk factor for significantly raised next day IOP and these patients are more likely to experience postoperative discomfort. They may benefit from prophylactic treatment.

A novel use of amniotic membrane in the management of tube exposure following glaucoma tube shunt surgery.

AIM: To report a novel technique using amniotic membrane to cover exposed glaucoma tube shunts. METHODS: A consecutive series of three cases that underwent drainage tube shunt surgery with the Ahmed valve for intractable glaucoma. All three patients developed exposure of the tube secondary to necrosis of the overlying bovine pericardial patch and conjunctiva. Repair of the defect was carried out with a double layer of amniotic membrane, the inner one acting as a graft and the outer as a patch. Autologous serum was used to promote epithelial growth. RESULTS: Successful lasting closure of the conjunctival defect was achieved in all cases. CONCLUSION: Erosion of the drainage tube following shunt surgery is a potentially serious problem. It can be successfully managed using a double layer of amniotic membrane.

Epithelial proliferative potential of organ cultured corneoscleral rims; implications for allo-limbal transplantation and eye banking.

AIMS: To determine the epithelial proliferative capacity of organ cultured limbal tissue and correlate this with various donor and eye banking factors. METHODS: 24 corneoscleral limbal (CSL) rims left over from penetrating keratoplasty were split in half and set up as in vitro explant cultures. Corneal epithelial proliferative potential (CEPP) was assessed by the number of "cycles" of growth achieved before explants underwent exhaustion and failure to generate an epithelium to subconfluence. The dependence of CEPP on the age of the donor, time of death to enucleation, time of enucleation to organ culture, and time in organ culture in the eye bank was determined. RESULTS: CSL rims were capable of up to four cycles of culture with a wide variation between tissue samples. Of the various factors examined, death to enucleation time was the only statistically significant factor affecting the CEPP (regression coefficient: -0.062 (cycles/hour), CI -0.119 to -0.004, p = 0.037). Time in organ culture had little effect on CEPP. CONCLUSIONS: Preselected organ cultured CSL rims from eye banks may offer a viable alternative tissue source for use in allo-limbal transplantation.

What is practical in glaucoma management?

This article addresses some important issues in the detection and management of glaucoma using examples from the developing world, particularly drawing on experiences and research in sub-Saharan Africa.

The effect of corneal thickness on intraocular pressure measurement in patients with corneal pathology.

BACKGROUND/AIM: To compare intraocular pressure (IOP) measurements taken by the Goldmann applanation tonometer, the Tono-Pen and the ocular blood flow pneumotonometer in eyes with varying central corneal thickness (CCT) due to penetrating keratoplasty (PK), keratoconus (KC), and Fuchs' endothelial dystrophy (FED). METHODS: IOP was measured with the Goldmann applanation tonometer, Tono-Pen XL, and OBF pneumotonometer in 127 eyes with the following corneal abnormalities. There were 56 eyes that had undergone PK, 37 eyes with KC, and 34 eyes with FED. CCT was measured using an ultrasound pachymeter after IOP determinations had been made. RESULTS: Mean IOP measurements in all three patient groups were significantly higher when measured by OBF pneumotonometer. Linear regression analysis showed that patients with FED had a significant increase in IOP with increasing CCT of 0.18 mm Hg/10 microm using the Goldmann tonometer, 0.15 mm Hg/10 microm with the Tono-Pen, and 0.26 mm Hg/10 microm with the OBF pneumotonometer. In patients with KC and after PK, linear regression analysis did not show a significant effect of CCT on IOP. A multivariate linear regression model controlling for age, sex, graft size, and patient group, showed that the effect of CCT on IOP for Tono-Pen (0.13 mm Hg/10 microm CCT) and Goldmann (0.14 mm Hg/10 microm CCT) were significantly lower than for the OBF pneumotonometer (0.26 mm Hg/10 microm CCT). CONCLUSIONS: This study found that mean IOP measurements using the OBF pneumotonometer were significantly higher than those made using the Goldmann applanation tonometer or Tono-Pen in eyes with a variety of cornel pathologies. The OBF pneumotonometer was found to be most affected by variation in CCT. For all three instruments, the relation between IOP and CCT depended on the corneal pathology and was greatest for FED.

Diabetes in rural South Africa--an assessment of care and complications.

OBJECTIVES: To describe the diabetic population under care of the public health sector in a district in rural KwaZulu-Natal, to assess the nature of their care, their glycaemic control and the extent of their complications. SUBJECTS AND METHODS: Two hundred and fifty-three diabetic patients consecutively attending clinics for review were interviewed and examined, and where available a 12-month retrospective review of clinical records was performed. Random blood glucose, haemoglobin A1c (HbA1c) and urine albumin/creatinine ratio were assayed. RESULTS: Acceptable glycaemic control (HbA1c < 2% above normal population range) was found in only 15.7% of subjects (95% confidence interval (CI): 11.4-20.8%). Mean HbA1c was 11.3%. The prevalence of hypertension (blood pressure > or = 160/95 mmHg and/or prescribed antihypertensive medication) was 65.4% (CI: 59.0-71.1%). Of 129 patients who were prescribed antihypertensives, 14.0% (CI: 8.5-21.2%) were normotensive (< 140/90 mmHg). Severe obesity was present in 36.5% (CI: 30.4-42.9%). Rates of attendance for review and compliance with diabetic medications were high. Blood glucose monitoring was not regularly performed and medications were rarely modified. Complications were common and mostly undiagnosed. Retinopathy of any grade was found in 40.3% of patients (CI: 33.2-50.9%) and was severe enough to warrant laser photocoagulation in 11.1% (CI: 8.5-21.2%). Microalbuminuria was found in 46.4% (CI: 40.0-53.0%) and foot abnormalities attributable to diabetes in 6.0% (CI: 3.4-9.7%). CONCLUSIONS: Care and control of diabetes in this rural community is suboptimal. There is a need for primary care staff to focus on modifying prescriptions in the face of poor blood glucose control and/or uncontrolled hypertension. Additional training and support for nursing staff and education for patients will be central to achieving this level of intervention.

Reasons for poor cataract surgery uptake - a qualitative study in rural South Africa.

OBJECTIVES: To understand the reasons for poor cataract surgery uptake in people with blindness or severe visual impairment in rural South Africa. METHODS: A qualitative analysis of detailed, domiciliary interviews with a community-based random sample of elderly Zulus who were blind or severely visually impaired as a result of operable cataract, who had previously been invited for surgery but had failed to attend. RESULTS: Fear of surgery and a fatalistic attitude to the inevitability and irreversibility of blindness in old age were the main reasons for failure to attend for surgery. There was a lower level of disability and perceived need than had been assumed for people with such poor visual acuity. Non-surgical western style health care for systemic illness was common but few patients had sought any form of assistance for their poor vision. Issues of cost and accessibility were relatively unimportant. CONCLUSION: Provision of affordable and accessible cataract surgery for the blind and severely visually impaired members of a community does not guarantee that it will be taken up. Other barriers to surgery may be revealed when practical issues such as cost and accessibility are addressed. Perceptions of visual disability among subjects with cataract may differ from simple objective clinical standards.

Assessing diabetic control--reliability of methods available in resource poor settings.

AIMS AND METHODS: To examine the reliability of random venous or capillary blood glucose testing, random urine glucose testing, and a current symptom history in predicting a high HbA1c in Type 2 diabetic patients taking oral hypoglycaemic agents in a poorly controlled rural African population. RESULTS: For a cut-off point for HbA1c of > or = 8%, for random venous plasma glucose of > or = 14 mmol/L (present in 47.2% of subjects), specificity was 97.1% (95% CI 85.1-99.9), sensitivity 56.8% (48.8-64.5) and positive predictive value (PPV) 98.9% (94.2-99.9). HbA1c > or = 8% is predicted by a random capillary blood glucose of 17 mmol/L (present in 28.4% of subjects) with specificity 100% (90.0-100.0), PPV 100% (93.7-100.0) and sensitivity of 34.3% (27.2-42.1). HbA1c > or = 8% is predicted by the presence of heavy glycosuria (> or = 55 mmol/L) (present in 35.6%) with specificity 94.1% (80.3-99.3), sensitivity of 41.9% (34.1-49.9) and PPV 97.1% (89.9-99.6). Polyuria/nocturia (present in 31.3%) was the only symptom found to be associated with poor control, with a specificity for predicting HbA1c of > or = 8% of 81.5% (61.9-93.7), PPV 89.1% (76.4-96.4) and sensitivity 30.6% (22.9-39.1). CONCLUSIONS: Where resources are short, random glucose testing can be used to detect a significant proportion of those with the worst control with a high degree of specificity enabling primary care staff to modify treatment safely. Where facilities are limited capillary blood or urine testing with reagent strips, may be substituted for venous plasma testing in the laboratory. A symptom history was insufficient to replace biochemical testing, but where this is unavailable, urinary symptoms may be helpful.

Rapid assessment of cataract surgical coverage in rural Zululand.

OBJECTIVE: Cataract surgical coverage (CSC) is a useful indicator of the degree of success of a cataract intervention programme. However, because previously described methods are time-consuming and labour-intensive, they are rarely performed. This study describes a simple and inexpensive assessment of CSC based on screening of pensioners at pension delivery sites in a rural district. DESIGN: Random cluster-based cross-sectional survey. SETTING: State pension distribution sites in Hlabisa, a rural district in KwaZulu-Natal, South Africa. SUBJECTS: 562 old-age pensioners. METHOD: Subjects found to be blind (visual acuity < 3/60) and those reporting a history of eye surgery were examined using a torch and direct ophthalmoscope by an ophthalmologist. OUTCOME MEASURES: Cases of blindness due to operable cataract and post-cataract surgical subjects were identified. RESULTS: CSC was found to be 38.5% (95% confidence interval 29.1-47.9%). Blindness prevalence was 10.3%, with 69.0% due to cataract.

Compliance with timolol treatment in glaucoma.

PURPOSE: To assess levels of compliance in elderly patients on timolol eyedrops for glaucoma. METHODS: A postal questionnaire was sent from the general practitioner to 86 patients over 55 years of age on repeat prescriptions for timolol eyedrops. The questionnaire asked details about the duration of treatment, family history, the level of understanding of the disease and the importance of treatment, other regular medication, side-effects attributed to the drops and how often patients omitted their drops. A search of practice and local hospital dispensing data was carried out to assess how frequently monthly repeat prescriptions for timolol eyedrops were dispensed over a 12 month period. This allowed a total volume to be calculated for each patient. RESULTS: Twenty-four per cent of patients admitted to omitting eyedrops either occasionally or frequently. Fifty-one per cent were found to have had insufficient drops dispensed to comply with treatment as prescribed. In non-complaint patients the mean period without drops was 85 days of the year, with a maximum of 165 days. CONCLUSION: Compliance with treatment is poor and patients underestimate their level of defaulting when questioned.