Long-term anatomical and functional findings of solar maculopathy

BACKGROUND

Solar maculopathy (SM) is a rare cause of acquired maculopathy related to direct viewing of the sun. Primary symptoms include central scotomata, blurred vision and/or metamorphopsia due to thermal/photochemical damage to foveal photoreceptors.

METHODS

Patients were identified from clinic records surrounding a solar eclipse. Clinical examination and multimodal retinal imaging were performed at each follow-up visit. Informed consent was provided by each patient for publication of anonymized data.

RESULTS

Seven affected eyes of 4 patients (mean 21.75 years, all female) were identified with mean presenting visual acuity (VA) of LogMAR 0.18. Well-defined photoreceptor ellipsoid zone (EZ) defects were identified on optical coherence tomography (OCT) for all eyes. VA improved for all eyes (median 12 letter improvement) over a mean 5.7-year follow-up (range 5 months to 11 years).

CONCLUSIONS

While no effective treatment has been identified for SM, VA can significantly improve in some cases, but persistent scotomata are reported and may be debilitating; thus, prevention by public health measures remains critical.

Measurement of the retinal arteriolar response to a hyperoxic provocation in nonsmokers and smokers, using a high-resolution confocal scanning laser ophthalmoscope

We used a high-resolution confocal scanning laser ophthalmoscope to measure the magnitude of change in retinal arteriolar diameters in response to oxygen breathing in young, healthy nonsmokers and smokers. Image sequences were obtained before and during oxygen breathing. Image sequences were desinusoided, registered, and averaged, before vessel diameters were measured using a sliding linear regression filter. Arteriole diameters were observed to constrict during the first 5 min. of oxygen breathing, plateau, and remain stable while hyperoxia was maintained, returning to baseline at the end of the hyperoxic period. Blood flow to the temporal retina was found to be higher than to the nasal retina (p=0.008). The percentage constriction of vessels did not vary across retinal quadrants (p=0.372, analysis of variance) and did not depend on vessel size (p=0.538). Baseline diameters were unaffected by acute cigarette smoking. The magnitude of vasoconstriction was diminished in smokers compared to nonsmokers (p=0.017), while acute smoking did not influence the percentage constriction attained by the vessels (p=0.621). Using a high-resolution imaging technique allowed us to measure reactivity to a high degree of accuracy and to assess it in vessels of smaller caliber than were previously studied.

A national house-staff audit of medical prophylaxis in medical patients for the PREVENTion of Venous ThromboEmbolism (PREVENT-VTE)

We established a national audit to assess the thromboprophylaxis rate for venous thromoembolism (VTE) in at risk medical patients in acute hospitals in the Republic of Ireland and to determine whether the use of stickers to alert physicians regarding thromboprophylaxis would double the rate prophylaxis in a follow-up audit. 651 acute medical admission patients in the first audit and 524 in the second re-audit were recruited. The mean age was 66.5 yrs with similar numbers of male and female patients and 265 (22.6%) patients were active smokers. The first and second audits identified 549 (84%) and 487 (93%) of patients at-risk for VTE respectively. Of the at-risk patients, 163 (29.7%) and 132 (27.1%) received LMWH in the first and second audit respectively. Mechanical thromboprophylaxis was instigated in 75 (13.6%) patients in the first and 86 (17.7%) patients in the second audit. The placement of stickers in patient charts didn't produce a significant increase in the number of at risk patients treated in the second audit. There is unacceptably low adherence to the ACCP guidelines in Ireland and more complex intervention than chart reminders are required to improve compliance.

Solar retinopathy secondary to sungazing

A young woman presented with a 2-day history of bilateral central scotoma and metamorphopsia following an episode of direct sun-gazing lasting 1-2 min. On examination, visual acuity was reduced to 6/9 bilaterally. Fundal examination revealed discrete yellow lesions at both maculae consistent with solar burns. Optical coherence tomography revealed retinal pigment epithelial defects at both fovea, which improved over time. The patient was managed conservatively. There was full resolution of symptoms in the left eye; however, a central scotoma persisted in the right eye at follow-up 1 year later.

Long term results of diode laser cycloablation in complex glaucoma using the Zeiss Visulas II system

AIM

To investigate the safety and efficacy of the Zeiss Visulas II diode laser system in the reduction of intraocular pressure (IOP) in patients with complex glaucoma.

METHODS

The authors analysed the medical records of patients who underwent trans-scleral diode laser cycloablation (TDC) at the Manchester Royal Eye Hospital during a 34 month period. 55 eyes of 53 patients with complex glaucoma were followed up for a period of 12-52 months (mean 23.1 months) after initial treatment with the Zeiss Visulas II diode laser system.

RESULTS

Mean pretreatment IOP was 35.8 mm Hg (range 22-64 mm Hg). At the last examination, mean IOP was 17.3 mm Hg (range 0-40 mm Hg). After treatment, 45 eyes (82%) had an IOP between 5 and 22 mm Hg; in 46 eyes (84%) the preoperative IOP had been reduced by 30% or more. The mean number of treatment sessions was 1.7 (range 1-6). At the last follow up appointment, the mean number of glaucoma medications was reduced from 2.1 to 1.6 (p<0.05). In 10 eyes (18%), post-treatment visual acuity (VA) was worse than pretreatment VA by 2 or more lines.

CONCLUSIONS

Treatment with the Zeiss Visulas II diode laser system can be safely repeated in order to achieve the target IOP. Treatment outcomes in this study were similar to those from previously published work using the Iris Medical Oculight SLx laser.

Glycoproteins of trabecular meshwork, cornea and sclera

PURPOSE

To analyse high-molecular-weight matrix glycoproteins in trabecular meshwork, cornea and sclera using SDS/PAGE and immuno- and lectin blotting.

METHOD

Extracts of normal trabecular meshwork (TM), cornea and sclera were analysed under reducing conditions on SDS/ PAGE. Western blots were stained for total protein, and major high-molecular-weight components were identified by immunoblotting with antibodies to fibronectin (FN) and type VI collagen. Lectin blotting with PSA, MPA and DSA identified some of the glycoprotein glycans.

RESULTS

FN antibody bound to the 240 kDa band in TM, cornea and sclera. Type VI collagen antibody bound more strongly to one band and less so to two other bands at approximately 200 kDA in normal TM and to a ladder of bands in cornea and sclera. PSA and DSA bound at 240, 200 and 140 kDa in TM, cornea and sclera. MPA bound at 240, 200 and 140 kDa in TM and at 240, 200 and approximately 120 kDA in cornea and sclera.

CONCLUSIONS

FN is a component of the band at 240 kDA in TM, cornea and sclera. Normal TM was found to contain relatively more of one of the isoforms of the alpha 3 (VI) chain whilst cornea and sclera contained all the alpha 3 (VI) isoforms. Complex N-linked bi/tri-antennary glycans were localised in FN and the alpha 1, alpha 2 and alpha 3 (VI) chains in TM, cornea and sclera. O-linked glycans (identified by MPA binding) were located in FN and alpha 3 (VI) chains of TM, cornea and sclera.

Spectral sensitivity in patients with dysthyroid eye disease

The majority of patients with dysthyroid eye disease have an acquired colour vision defect. However, no psychophysical investigation of selective damage to colour or flicker pathways has been carried out. In order to clarify the nature of the visual pathology, we have used a psychophysical technique (spectral sensitivity) to selectively stimulate the chromatic and achromatic mechanisms. Spectral spots of size 1 degree presented at a rate of 1 Hz on a bright 1000 td white background are detected by the chromatic mechanism but a rate of 25 Hz reveals the achromatic mechanism. Fifteen patients (28 eyes) between the ages of 50-70 years were tested. The study showed that all patients had reduced spectral sensitivity, either 1 Hz, 25 Hz or both. The patients with reduced 1 Hz or 25 Hz spectral sensitivity only had a shorter systemic and ocular duration of the condition, had no proptosis, normal intraocular pressures in primary gaze, slightly higher intraocular pressures on upgaze, normal visual field plots and FM 100-Hue error scores higher than the normal age-matched values. The patients with reduced both 1 Hz and 25 Hz spectral sensitivities had a longer systemic and ocular duration of the condition, had proptosis, normal intraocular pressures in primary position, higher intraocular pressures on upgaze and higher FM 100-Hue error scores than the age-matched normals and those in Groups 1 and 2. A total of 50% of patients in Group 3 had defective visual field plots. These data suggest that there is a damage of the large achromatic fibres and small chromatic fibres in dysthyroid eye disease. The mechanism of the damage could be one of ischaemic or mechanical or both.

Glycans of the trabecular meshwork in primary open angle glaucoma

AIMS

Glycan expression was compared in glaucomatous trabecular meshwork (TM) and normal TM in order to determine any differences which may reflect pathological changes underlying primary open angle glaucoma (POAG).

METHODS

Resin embedded TM from trabeculectomy specimens from 15 eyes with POAG and from 12 eyes with normal anterior segments were probed with a panel of biotinylated lectins and an avidin-peroxidase revealing system at the light microscope level. Statistical analyses were performed on the comparative staining results.

RESULTS

The lectins ConA and ePHA showed strong staining in all areas of both glaucomatous and normal TM; ePHA staining of Schlemm's canal (SC) from POAG TM was significantly less than that from normal TM (ePHA-SC p = 0.04). The lectins PSA, LCA, and SNA bound moderately strongly to SC endothelium and weakly to the endothelium of the corneoscleral meshwork (CSM); glaucomatous SC endothelial binding was significantly less than that of normal SC endothelium for PSA and LCA (PSA-SC p = 0.002, LCA-SC p = 0.002). STA and DSA showed moderately strong binding while WGA, ECA, AHA, and MPA bound weakly throughout the TM; for DSA and MPA this staining was significantly greater in POAG than in normal TM (DSA-SC p = 0.001, DSA-CSM p = 0.002, MPA-SC p = 0.01, MPA-CSM p = 0.02). Jac stained strongly throughout the TM and showed no significant difference in POAG compared with normal TM (Jac-SC p = 0.6, Jac-CSM p = 1). 1PHA, SBA, DBA, CTA, UEA-1 and LTA did not bind to glaucomatous TM or normal TM. There were no age-related changes seen.

CONCLUSIONS

The expression of some complex and hybrid, bisected and non-bisected N-linked glycans is significantly diminished in glaucomatous TM compared with normal TM. Some glycans with multiple N-acetylglucosamine residues and O-linked glycans with terminal and subterminal galactosyl groups are significantly increased in POAG TM. Glycan expression does not change significantly with age in POAG or normal TM.

Macrophages during fibrosis following scleral fistulising surgery in a rat model

PURPOSE

Glaucoma filtration surgery can fail in a minority of patients as a result of fibrosis in the subconjunctival bleb space and closure of the scleral fistula. In this study, the rat eye has been used as an experimental model for fistulising surgery in order to evaluate the clinical manifestation of bleb failure with the morphological events of the wound healing process.

METHODS

A conjunctival bleb was successfully formed in 25 rats and was examined daily using slit lamp microscopy to evaluate postoperative inflammation and the presence of a bleb. At defined post-operative time points, serial frozen sections of eyes were stained immunohistochemically using a panel of monoclonal antibodies directed against known surface markers on rat immune/inflammatory cells. Positively stained cells were counted (a) in the bleb site, (b) at the sclerostomy and (c) at the suture site.

RESULTS

Following an initial post-operative inflammation, a surgically formed sclerostomy and conjunctival bleb underwent a granulation and scarring response so that by 7-19 days the bleb had disappeared. Using the monoclonal antibodies applied in this study, it was possible to show that macrophages most likely play a major and pivotal role throughout the sequence of events that lead to repair of the fistula and closure of the bleb. It was also noted that the presence of an otherwise inert nylon suture used to close the incised conjunctiva can serve as a focus for macrophages.

CONCLUSION

The rat has been successfully used as an experimental model of fistulising surgery and its subsequent failure. The use of a panel of monoclonal antibodies directed against specific surface markers on immune-inflammatory cells, highlighted macrophages to be prominent in all stages of this wound healing process.

Glycoconjugates of the human trabecular meshwork: a lectin histochemical study

Twelve specimens of resin-embedded human trabecular meshwork were probed with a panel of 21 biotinylated lectins, using an avidin-biotin peroxidase revealing system, in order to determine the normal pattern of saccharide expression in this tissue. High-mannose, intermediate and hybrid N-linked glycans, and complex N-linked bisected and non-bisected bi/tri-antennate glycans, as shown by the binding of Canavalia ensiformis (ConA), Pisum sativum (PSA), Lens culinaris (LCA) agglutinins and Phaseolus vulgaris erythroagglutinin (ePHA), were strongly expressed by the canal of Schlemm endothelium and juxtacanalicular tissue, but less so by the corneoscleal meshwork. Highly branced complex glycans were not found, as there was no binding by Phaseolus vulgaris leukoagglutinin (IPHA). Sialyl residues, especially those alpha 2,6-linked as demonstrated by strong Sambucus nigra (SNA) lectin staining, were also abundant in this area. N-acetyllactosamine sequences and some O-linked glycans were present in the trabecular meshwork, as shown by Solanum tuberosum (STA), Datura stramonium (DSA), and Jacalin (Jac) lectin binding, while fucose residues were not detected by Tetragonolobus purpureas (LTA) or Ulex europaeus-1 (UEA-1) agglutinins. These results indicate similarities with renal glomerular and vascular endothelium, although the lack of binding with UEA-1 agglutinin suggests differences which may relate to the specialized function of the trabecular meshwork. This study provides a baseline for comparative analysis of the glycans of human trabecular meshwork in pathological conditions such as primary open-angle glaucoma.

Effect on intraocular pressure of local anaesthesia in eyes undergoing intraocular surgery

A total of 104 eyes undergoing intraocular surgery were studied to investigate the effect on intraocular pressure (IOP) of peribulbar and retrobulbar anaesthesia in eyes with and without glaucoma. Forty eyes had glaucoma. Intraocular pressure was measured before, immediately after, and 5 minutes after injection of local anaesthetic. Mean IOP rose by 5.8 mm Hg at 1 minute (p < 0.01) and 0.7 mm Hg at 5 minutes (p > 0.05). However, in eyes not receiving external ocular compression after the 1 minute measurement (n = 70, 67%), IOP was still 3.6 mm Hg higher than baseline (p < 0.01), compared with 5.2 mm Hg lower than baseline (p < 0.01) where compression was used. Patients with glaucoma experienced higher and more persistent increases in IOP than those without glaucoma. The increase in IOP varied greatly between patients: the maximum rise was 25 mm Hg, and in one glaucoma patient an IOP of 50 mm Hg occurred, persisting for 5 minutes. At 1 minute, 14 of the glaucoma subjects (35%) had experienced an IOP rise of > or = 10 mm Hg, and four (10%) a rise of > or = 20 mm Hg. These results suggest that the changes in IOP in patients with glaucoma, with an acute increase in IOP being succeeded by an acute decrease on entry into the anterior chamber, may be hazardous. The implications for clinical practice are discussed.

Novel electrochemical device for the detection of cholesterol or glucose

A thin-layer twin-electrode electrochemical cell in which the working and auxiliary electrodes are facing each other and which contains the appropriate enzyme and a mediator was used for the determination of cholesterol or glucose. A steady-state diffusion-controlled response was obtained for cholesterol whereas for glucose the response was limited by diffusion and kinetics. Simulation of the system showed that a steady-state response is obtained, in the absence of kinetic complications, after a time of 0.01 d2/Ds, where d is the distance between the two electrodes and D is the diffusion coefficient of the mediator. Linear plots of steady-state current versus concentration were obtained for cholesterol and glucose. The results were compared with those expected theoretically and a thin-layer capillary fill device is proposed.

Surgically induced necrotising sclerokeratitis (SINS)--precipitating factors and response to treatment

The clinical features, treatment, and visual outcome of 52 eyes from 43 patients who developed scleritis following surgery were reviewed. In all patients the scleral inflammation developed adjacent to a surgical wound. Ninety six per cent had necrotising disease and 23% also had evidence of secondary posterior scleritis. Many different types of ocular surgery were implicated and the majority (75%) of the patients had two or more surgical procedures before the onset of the scleritis. Although cataract extraction through a limbal incision resulted in the largest subgroup, scleritis also followed glaucoma, strabismus, and retinal detachment surgery. The latent period between surgery and the appearance of inflammation was short (mean 9 months) except for a small group in whom scleritis occurred many years after squint surgery. Sixty three per cent of patients had evidence of a systemic disease. Early diagnosis and aggressive medical treatment significantly improved the visual outcome. The precipitating factors, pathogenesis, and course of this condition are discussed.

The provision of ophthalmic services for a rehabilitation day care centre population with multiple physical handicaps

The provision of the wide variety of support services necessary for patients with multiple handicaps is often poorly coordinated. In this study a group of 108 adults, aged from 19 to 90 years, who suffered from multiple physical handicaps and attended a rehabilitation day care centre, had their visual functions and requirements assessed by a multidisciplinary team. The programme consisted of five stages. Each patient was initially screened and subsequently referred for more detailed optometric, ophthalmological, low vision or rehabilitation assessments, where appropriate. Results indicated that many of the patients had not been receiving regular ocular assessments and would benefit from the provision of an optical appliance or ophthalmological treatment. The survey provided staff at the rehabilitation centre with information on the visual status of individual patients and enhanced general eye-care awareness.

Peripheral contrast sensitivity in glaucoma and ocular hypertension

Contrast sensitivity has been measured in patients with glaucoma and ocular hypertension, the latter graded into high, medium, and low risk clinical groups. Measurements were made centrally and peripherally at 10 degrees, 15 degrees, 20 degrees, and 25 degrees off-axis at each of the four meridians 45 degrees, 135 degrees, 225 degrees, and 315 degrees. A sine wave grating of 1.9 cycles/degree, reversing at 1 Hz was used. It was displayed on a 100-Hz refresh rate monitor. Normal values were established to compare those from 41 eyes from patients with either primary open angle glaucoma (POAG) with minimal field loss detectable on a Humphrey perimeter, or raised IOP and/or disc changes but no field loss (OH). Those with POAG had normal central contrast sensitivity, but at 20 degrees and 25 degrees eccentricity the values were greater than 2 standard deviations above the normal mean. This was also the case for high risk OH, but not for low risk patients. All the high risk patients except one who had abnormal peripheral contrast sensitivity had possible field defects (threshold elevation at one or more points more than 5 but less than 10 dB above normal mean). Only one of those with normal peripheral contrast sensitivity had such 'suspect points'. The results are assessed in terms of screening of glaucoma suspects.