Defining response to anti-VEGF therapies in neovascular AMD

The introduction of anti-vascular endothelial growth factor (anti-VEGF) has made significant impact on the reduction of the visual loss due to neovascular age-related macular degeneration (n-AMD). There are significant inter-individual differences in response to an anti-VEGF agent, made more complex by the availability of multiple anti-VEGF agents with different molecular configurations. The response to anti-VEGF therapy have been found to be dependent on a variety of factors including patient's age, lesion characteristics, lesion duration, baseline visual acuity (VA) and the presence of particular genotype risk alleles. Furthermore, a proportion of eyes with n-AMD show a decline in acuity or morphology, despite therapy or require very frequent re-treatment. There is currently no consensus as to how to classify optimal response, or lack of it, with these therapies. There is, in particular, confusion over terms such as 'responder status' after treatment for n-AMD, 'tachyphylaxis' and 'recalcitrant' n-AMD. This document aims to provide a consensus on definition/categorisation of the response of n-AMD to anti-VEGF therapies and on the time points at which response to treatment should be determined. Primary response is best determined at 1 month following the last initiation dose, while maintained treatment (secondary) response is determined any time after the 4th visit. In a particular eye, secondary responses do not mirror and cannot be predicted from that in the primary phase. Morphological and functional responses to anti-VEGF treatments, do not necessarily correlate, and may be dissociated in an individual eye. Furthermore, there is a ceiling effect that can negate the currently used functional metrics such as >5 letters improvement when the baseline VA is good (ETDRS>70 letters). It is therefore important to use a combination of both the parameters in determining the response.The following are proposed definitions: optimal (good) response is defined as when there is resolution of fluid (intraretinal fluid; IRF, subretinal fluid; SRF and retinal thickening), and/or improvement of >5 letters, subject to the ceiling effect of good starting VA. Poor response is defined as <25% reduction from the baseline in the central retinal thickness (CRT), with persistent or new IRF, SRF or minimal or change in VA (that is, change in VA of 0+4 letters). Non-response is defined as an increase in fluid (IRF, SRF and CRT), or increasing haemorrhage compared with the baseline and/or loss of >5 letters compared with the baseline or best corrected vision subsequently. Poor or non-response to anti-VEGF may be due to clinical factors including suboptimal dosing than that required by a particular patient, increased dosing intervals, treatment initiation when disease is already at an advanced or chronic stage), cellular mechanisms, lesion type, genetic variation and potential tachyphylaxis); non-clinical factors including poor access to clinics or delayed appointments may also result in poor treatment outcomes. In eyes classified as good responders, treatment should be continued with the same agent when disease activity is present or reactivation occurs following temporary dose holding. In eyes that show partial response, treatment may be continued, although re-evaluation with further imaging may be required to exclude confounding factors. Where there is persistent, unchanging accumulated fluid following three consecutive injections at monthly intervals, treatment may be withheld temporarily, but recommenced with the same or alternative anti-VEGF if the fluid subsequently increases (lesion considered active). Poor or non-response to anti-VEGF treatments requires re-evaluation of diagnosis and if necessary switch to alternative therapies including other anti-VEGF agents and/or with photodynamic therapy (PDT). Idiopathic polypoidal choroidopathy may require treatment with PDT monotherapy or combination with anti-VEGF. A committee comprised of retinal specialists with experience of managing patients with n-AMD similar to that which developed the Royal College of Ophthalmologists Guidelines to Ranibizumab was assembled. Individual aspects of the guidelines were proposed by the committee lead (WMA) based on relevant reference to published evidence base following a search of Medline and circulated to all committee members for discussion before approval or modification. Each draft was modified according to feedback from committee members until unanimous approval was obtained in the final draft. A system for categorising the range of responsiveness of n-AMD lesions to anti-VEGF therapy is proposed. The proposal is based primarily on morphological criteria but functional criteria have been included. Recommendations have been made on when to consider discontinuation of therapy either because of success or futility. These guidelines should help clinical decision-making and may prevent over and/or undertreatment with anti-VEGF therapy.

Quality of bevacizumab compounded for intravitreal administration

AIM

To compare the quality and stability of unlicensed, repackaged bevacizumab intended for intravitreal injection, as provided by five licensed compounding pharmacies in the United Kingdom, with bevacizumab in its original glass vial.

METHODS

Repackaged bevacizumab was obtained from five UK suppliers. Samples were analyzed at two time points (day 1 and day 14). Microflow imaging was performed to evaluate subvisible particle size, particle density, and particle size distribution. Protein concentration, immunoglobulin G (IgG) content, and molecular weight were also determined.

RESULTS

A significant difference in subvisible particle density was observed between bevacizumab batches from the five suppliers on day 1 (P<0.001). An increase in subvisible particle density was observed between day 1 and 14 for repackaged bevacizumab from all suppliers (all P<0.05), but not the reference compound. Protein concentration, IgG content, and molecular weight were comparable between batches from each supplier and the reference bevacizumab.

DISCUSSION

The study results indicate that the quality of bevacizumab repackaged into prefilled plastic syringes is variable among the different compounding pharmacies in the United Kingdom. Furthermore, particle density may increase with storage in repackaged syringes. It is noteworthy that particle size distribution in both the repackaged and reference bevacizumab fell outside of the range specified by the United States Pharmacopeia for injectable ophthalmic solutions. These data highlight the need for further research into the use of unlicensed, repackaged bevacizumab intended for intravitreal injection.

Central retinal artery occlusion following peribulbar anesthesia for pterygium excision

Pterygium is a common ocular surface pathology in tropical environments. In the early stages, it may be managed medically with topical anti-inflammatory agents and ocular lubricants. However as the disease progresses, surgical excision becomes necessary and several anaesthetic methods may be used to assist this. We share our experience of a 30-year old woman who underwent uneventful pterygium excision using peribulbar lignocain injection with adrenaline. She developed sudden blindness due to central retinal artery occlusion with macular infarction. While peribulbar anaesthesia is generally safe, a remote risk of retinal vascular accident exists and its routine use should be done with caution. Where possible topical anaesthesia with or without intra-lesional injection be employed.

Causes and incidence of destructive eye procedures in north-eastern ghana

OBJECTIVE

To determine the causes and incidence of destructive ophthalmic procedures as seen at a major reference eye centre in northern Ghana

METHODS

Retrospective case series involving a review of surgical records of all evisceration and enucleation procedures done between January 2002 and December 2006 at the Bawku Hospital Eye Department. Information collected included basic demographic data, diagnosis, visual acuity at diagnosis and the eye affected. The aetiology responsible was determined from history, clinical examination and investigations as contained in the existing records. The primary clinical indications for evisceration were categorized into degenerative lesions, infections, trauma, neoplasms, and others. Statistical analysis was done using the Epi Info software.

RESULTS

A total of 337 eyes of 336 patients made up of 217 (64.6%) males and 119 (35.4%) females were removed during the study period. Mean age was 36.4 with a range of 1-90 years. Children under 15 years constituted 25.1% of whom 9.3% were under 5 years. The elderly (>/=60 years) comprised 26.3%. The most common cause of destructive procedure was endophthalmitis /panophthalmitis (47.9%), ocular injuries (23.2%), degenerative lesions (8.9%) and neoplasms (5.1%). Regarding neoplasms, females were more likely to be enucleated while the reverse was so for traumas (p=0.04 and p=0.02, Chi(2) test, respectively). Compared to the total number of surgeries done each year the crude incidence was computed at 26.6% per 1000 cases per year.

CONCLUSION

Most causes of destructive procedures in this part of Ghana are preventable and serious preventive strategies are needed to reverse this trend.

The effects of growth factors on the proliferation and in vitro angiogenesis of human macular inner choroidal endothelial cells

AIM

To investigate the effect of VEGF(165), FGF2, IGF-1, PDGF-AA, PDGF-BB and IL-1 beta on the proliferation and angiogenic tube formation of human macular inner choroidal endothelial cells (ICEC).

METHODS

The proliferation of human macular ICECs after exposure to the aforementioned growth factors was determined by using both a WST-1 colorimetric assay and a cell-counting technique. The effect of growth factors on ICEC angiogenesis was assessed by sprout formation using a three-dimensional in vitro Matrigel duplex assay.

RESULTS

Using both the WST-1 assay and a cell-counting technique, VEGF(165) and FGF2 both significantly increased human macular ICEC proliferation. The effect of equimolar concentrations of VEGF(165) and FGF2 was additive. There was no significant effect for IGF-1, PDGF-AA, PDGF-BB or IL-1 beta on proliferation up to a growth factor concentration of 1000 pmol/l. The angiogenesis assay found a significant effect on sprout formation for VEGF(165) and FGF-2. Again, the effect of equimolar concentrations of VEGF(165) and FGF2 was additive. There was no significant effect for IGF-1, PDGF-AA, PDGF-BB or IL-1 beta on sprout formation at 1000 pmol/l.

CONCLUSIONS

Both VEGF(165) and FGF2 significantly increase human macular ICEC proliferation and sprout formation in an angiogenesis assay. When present together, their effect was additive. IGF-1, PDGF-AA, PDGF-BB and IL-1 beta did not have any significant effect on proliferation or sprout formation in vitro. These results suggest that targeting other growth factors such as FGF2, in addition to VEGF, may be beneficial in the treatment of neovascular age-related macular degeneration.

Syphilitic acute posterior placoid chorioretinitis in nonimmuno-compromised patients

PURPOSE

To describe the clinical and angiographic features of three cases of secondary syphilis in immunocompetent patients, which presented as acute posterior placoid chorioretinitis (APPC) to the ophthalmologist.

METHODS

Interventional case series. The aetiology of the APPC was confirmed by serology to be secondary syphilis. Optical coherence tomography, electrophysiology, fundus fluorescein, and indocyanine green (ICG) angiography were performed at presentation and after resolution. Appropriate treatment for secondary syphilis was instituted in each patient.

RESULTS

The clinical features, fundus fluorescein and ICG angiography, multifocal electroretinography (mfERG), and optical coherence tomography findings of APPC are described. All three patients had a satisfactory resolution of the APPC with improvement in visual acuity.

CONCLUSIONS

APPC in secondary syphilis can occur even in immunocompetent patients. A high index of suspicion is required for early diagnosis of this condition resulting in a good visual outcome with adequate treatment. mfERG and optical coherence tomography are useful in the diagnosis and follow-up of these patients.

The management of retinal vein occlusion: is interventional ophthalmology the way forward?

Retinal vein occlusions (RVO) are the second commonest sight threatening vascular disorder. Despite its frequency treatments for RVO are unsatisfactory and include several that have not been tested by large, well designed, prospective, randomised controlled trials. There is also the lack of long term follow up in many of the available small uncontrolled studies, and the timings of interventions are haphazard. This review aims to evaluate the current knowledge relating to the pathogenesis, suggested treatments for the different types of RVO, and their complications. Isovolaemic haemodilution is of limited benefit and should be avoided in patients with concurrent cardiovascular, renal, or pulmonary morbidity. Evidence to date does not support any therapeutic benefit from radial optic neurotomy, optic nerve decompression, or arteriovenous crossing sheathotomy on its own. Vitrectomy combined with intravenous thrombolysis may offer promise for central RVO. Similarly, vitrectomy combined with arteriovenous sheathotomy intravenous tissue plasminogen activator may offer benefits for branch RVO. RVOs occur at significantly high frequency to allow future prospective randomised controlled studies to be conducted to evaluate the role of different therapeutic modalities singly or in combination.

Effect of age related macular degeneration on the Eger macular stressometer photostress recovery time

AIM

To assess the repeatability of Eger macular stressometer (EMS) measures of photostress recovery and determine their association with other measures of visual function.

METHODS

EMS photostress recovery time was measured in 90 patients with bilateral exudative age related macular degeneration (AMD), 19 with bilateral atrophic AMD and 47 with both forms of the condition (mean age 79 (SD 13) years). Measurements were made on two occasions separated by 1 year. Intrasession repeatability was assessed by repeating the measures after a 10 minute recovery period at the first visit. Distance visual acuity was measured with a logMAR chart, near visual acuity with a MNRead chart at 25 cm, contrast sensitivity with a Pelli-Robson chart, and the presence of central visual disturbance assessed with an Amsler grid. A questionnaire was used to assess self reported difficulties with glare recovery.

RESULTS

The average EMS recovery time was 11.0 (SD 8.9) seconds, decreasing by 1.6 (5.2) seconds on repeated measurement (p<0.05). EMS photostress recovery was not correlated with visual function measures or subjective difficulties with lights (p>0.05). EMS photostress recovery time did not predict those whose vision decreased over the following year compared with those among whom it remained stable.

CONCLUSIONS

The EMS test is not a useful tool in determining the severity or progression of AMD.

Isolation, culture, and characterisation of human macular inner choroidal microvascular endothelial cells

AIM

To develop a method for the reliable isolation of adult human macular inner choroidal endothelial cells (ICECs) and to subsequently characterise them for their expression of a range of endothelial cell associated surface markers.

METHOD

Human ICECs were isolated after manual dissection of maculas from fresh human posterior segments. Following enzyme digestion to form a single cell suspension, the ICECs were isolated using anti-CD31 coated Dynabeads. The isolated cells were grown in culture and examined for typical endothelial cell morphology, surface expression of vWf, CD 31, CD 105, VEGF receptors 1 and 2, and expression of E-selectin after stimulation with TNF-alpha. The cells were also examined for their ability to form fenestrations and capillary-like tubes in Matrigel.

RESULTS

The method enabled the rapid isolation of viable cells that demonstrated typical endothelial cobblestone morphology in culture. The cells stained positive for CD31, vWf, CD105, VEGF receptors 1 and 2, and E-selectin (after stimulation with TNF-alpha). The cells stained negative for alpha smooth muscle actin and fibroblast surface protein. The cells also developed fenestrations when cultured on fibronectin coated plates and formed capillary-like tubes structures when cultured on Matrigel.

CONCLUSIONS

This technique isolates cells from the human macular inner choroid that display features consistent with vascular endothelial cells. These cells could subsequently be used to further the understanding of the pathophysiological mechanisms of diseases of the inner choroid, such as choroidal neovascularisation.

Verteporfin photodynamic therapy of choroidal neovascularization in angioid streaks: one-year results of a prospective case series

PURPOSE

To report the 12-month results on the use of verteporfin photodynamic therapy (PDT) in the treatment of choroidal neovascularization (CNV) secondary to angioid streaks.

STUDY DESIGN

Five-center prospective case series.

METHODS

Patients with CNV secondary to angioid streaks who were treated with PDT were recruited and followed up at 3-month intervals for 12 months, with the addition of visits at 1.5 and 4.5 months if deemed appropriate by the investigator. Best-corrected visual acuity (BCVA) was measured at each visit after full refraction or with their current distance spectacles using Early Treatment Diabetic Retinopathy Study logarithm of the minimum angle of resolution charts. Stereoscopic fundus fluorescein angiography was used to determine baseline lesion characteristics and location.

RESULTS

Twenty-two patients were recruited (23 eyes, 16 with subfoveal CNV and 7 with juxtafoveal; all classic no occult). Seventeen patients (77%) had angioid streaks secondary to pseudoxanthoma elasticum. In the subfoveal group, median BCVA at baseline was 49 letters (approximate Snellen equivalent, 20/100) and was 46 at 12 months (approximate Snellen equivalent, 20/125). Twelve of 16 eyes (75%) lost fewer than 8 letters, whereas 14 of 16 eyes (88%) lost fewer than 15 letters. The mean CNV greatest linear dimension (GLD) was 2520 microm at baseline. At 12 months, 7 of 16 eyes with subfoveal CNV at baseline were leaking (GLD = 3220 microm; P = 0.62). The mean number of treatments in the first 12 months was 2.9. In the juxtafoveal group, the median BCVA at baseline was 66 letters (approximate Snellen equivalent, 20/50) and was 51 letters at 12 months (approximate Snellen equivalent, 20/100). Two of 7 eyes (29%) gained 8 or more letters at the 12-month examination, whereas 4 of 7 eyes (57%) lost more than 15 letters. The mean CNV GLD at baseline was 1890 microm. At 12 months, 1 of 7 eyes with juxtafoveal CNV at baseline was leaking. Choroidal neovascularization progressed from juxtafoveal to subfoveal location during the follow-up period in 4 of 7 eyes. The mean number of treatments in the first 12 months was 3.4. No side effects were noted in either patient group.

CONCLUSIONS

This small series suggests that treatment of CNV secondary to angioid streaks with verteporfin PDT seems to limit visual loss in most patients through the first 12 months of follow-up, particularly in those with subfoveal lesions at baseline.

The efficacy of sirolimus in the treatment of patients with refractory uveitis

AIMS

To determine the efficacy of sirolimus in the treatment of patients with severe non-infectious uveitis.

METHODS

Eight patients with severe non-infectious uveitis were recruited to an open study. Inclusion criteria were limited to patients whose disease was not controlled with at least two or more separate steroid sparing immunosuppressants (either because of unacceptable side effects or ineffectiveness of the drug) or who required regular doses of corticosteroids either as high dose systemic or orbital floor injections in order to control their disease. Intraocular inflammation, visual acuity, symptoms, corticosteroid burden, drug toxicity, and side effects were monitored.

RESULTS

Sirolimus therapy was effective in five of the eight patients, all of whom had their dose of corticosteroids reduced or discontinued. Treatment in three patients was considered a failure as it caused intolerable side effects and/or failed to control the uveitis. Side effects were common and were typically gastrointestinal or cutaneous in nature. The severity of symptoms was dose dependent in most cases and occurred at trough blood levels above 25 ng/ml.

CONCLUSION

Sirolimus is an effective and potent immunosuppressive treatment in the majority of patients with non-infectious uveitis and can reduce the need for long term supplementary corticosteroid therapy. Further studies are required to establish the long term efficacy and safety of sirolimus alone or in combination with other steroid sparing immunosuppressants.

Visual outcome of malignant hypertension in young people

A retrospective review was carried out of patients under 16 years old with malignant hypertension, who had been referred to a teaching hospital ophthalmology department because of reduced visual acuity. Four patients (three girls, one boy) were seen between 1994 and 2000 with a mean age at presentation of 11.5 years (range 9-15). In the short term, visual acuity improved after control of blood pressure in all four patients. However, in the long term, two patients were registered blind one to two years after presentation, one because of a choroidal neovascular membrane developing at the macula, and the other because of progressive optic neuropathy. Both of these patients had a longer duration of symptoms before diagnosis, worse visual acuity, and higher blood pressure at presentation when compared with the patients who made a good visual recovery. These observations suggest that early diagnosis of malignant hypertension in children is essential in reducing the likelihood of permanent severe visual damage.

Reproducibility of volumetric macular measurements in diabetic patients with the Heidelberg Retina Tomograph

AIMS

To quantify diabetic macular edema by confocal scanning laser ophthalmoscopy and assess its usefulness by determining the reproducibility of topographic measurements at the macula.

METHODS

The volumes above reference plane bound by a 2 mm diameter circle centred on the fovea were measured by two observers. The reference plane was adjusted to the lowest point of the height variation of the contour line. The reproducibility of this technique was assessed in 20 eyes of 20 diabetic patients of which 8 eyes had macular edema. Three HRT scans of each eye were obtained. The measurements of volume above reference plane of each scan were repeated three times.

RESULTS

For all diabetic eyes, the intra scan coefficients of variability measured 14.71% to 21.21%, the inter scan coefficient of variability was 30.46%. The average standard deviations were 0.053 mm3 for one examination per scan, 0.047 mm3 for two examinations per scan and 0.044 mm3 for three examinations per scan. Linear regression demonstrated an increase in standard deviation with greater volumetric measurements (p < 0.001). We found good correlation (r = 0.959, p < 0.001) and strong agreement between the two observer's findings for all 20 eyes. For the 8 eyes with macular edema, the coefficients of variability were similar to those calculated for all 20 eyes. The average SD for one examination per scan were 0.078 mm3, 0.069 mm3 for two examinations per scan and 0.062 mm3 for three examinations per scan. We found good correlation (r = 0.945, p < 0.001) and strong agreement between the two observer's findings in eyes with edema.

CONCLUSION

The reproducibility of this technique has been demonstrated in diabetic eyes. This may have useful clinical applications for the quantification of diabetic macular edema and monitoring of laser therapy.

The visual results and changes in retinopathy in diabetic patients following cataract surgery

INTRODUCTION

A study was designed to investigate the visual improvement and incidence of progression of retinopathy in diabetic patients following extracapsular cataract extraction or phacoemulsification. They were compared to a matched group of non-diabetic patients.

METHODS

A retrospective analysis of all diabetic patients (118) undergoing ECCE (90) or phacoemulsification (28) in 1995. These patients were operation and age matched with 118 non-diabetic patients who underwent surgery during the same year.

RESULTS

There was no statistically significant difference in complications following ECCE in diabetic and non-diabetic patients (p = 0.2). Complications were however more common in non-diabetic patients undergoing phacoemulsification compared to diabetics undergoing the same procedure (p = 0.046). Although consultants performed 42% of the surgery in diabetics compared to 31% in non-diabetics, there was no significant difference in the rate of complications between consultants and residents (p = 0.8). Overall the visual improvement in non-diabetics was better than diabetic patients (p = 0.006). This was due to a better improvement amongst non-diabetic patients undergoing phacoemulsification (p = 0.02). Overall, cataract surgery was found to lead to a worsening in retinopathy in 19 operated eyes (15 had no retinopathy preoperatively) compared to a worsening in 8 fellow eyes. This was statistically significant (p = 0.04). However, ECCE was no more likely to cause worsening of retinopathy than phacoemulsification (p = 0.87).

CONCLUSIONS

Diabetic patients due to undergo cataract surgery a) have a good chance of visual improvement but to a level less than if they were not diabetic, b) have a greater chance of visual loss, c) surgery may initiate or worsen any pre-existing retinopathy and this may affect their vision in the future.

Reproducibility of volumetric measurements of normal maculae with the Heidelberg retina tomograph

AIMS

The Heidelberg retina tomograph (HRT) is a scanning laser ophthalmoscope with confocal optics. The reproducibility of the optic nerve head topography is accurate and reliable. The authors describe a new technique for the assessment of macular thickening by volumetric quantification and present the results of its reproducibility in normal subjects.

METHODS

Topographic images of the macula, centred on the fovea were obtained in one eye of 44 normal subjects. The volumes above the reference plane bound by a 1 mm, 2 mm, and 3 mm diameter circle were measured. The reference plane was adjusted to the lowest point of the height variation of the contour line at each examination. The reproducibility of repeated measurements within a 2 mm diameter circle was assessed in 20 eyes selected at random. Three HRT scans of each eye were obtained. The measurements of volume above reference plane of each scan were repeated three times on three separate days.

RESULTS

The intrascan coefficients of variability measured 7.12-9.57%. The 95% confidence interval for the geometric mean ratio of single volume measurements was 0.92 to 1.24 for scans 1 and 2, 0.89 to 1.17 for scans 1 and 3, and 0.81 to 1.12 for scans 2 and 3. When the mean of three measurements of one scan were compared with the mean of three measurements of a second scan, the 95% confidence interval for their geometric mean ratio was 0.89 to 1.20 for scans 1 and 2, 0.89 to 1.16 for scans 1 and 3, and 0.84 to 1.13 for scans 2 and 3. The average standard deviation (SD) for one measurement per scan was 0.02 mm3, and 0.019 mm3 for two or three measurements per scan. Linear regression demonstrated a significant increase in SD as volumetric measurements increased (p = 0.003). Age did not significantly affect the SD of volumetric measurements (p = 0.797). The authors found no significant differences in volumetric measurements across all ages for all three circles (p = 0.314, p = 0.471, p = 0.267).

CONCLUSION

Good reproducibility for volumetric measurements at the macula was found with the HRT using the above technique in normal subjects. This method may be extremely useful for the identification and quantification of diabetic macular oedema and for monitoring the effects of argon laser photocoagulation.

Volumetric analysis of early macular edema with the Heidelberg Retina Tomograph in diabetic retinopathy

OBJECTIVE

This study describes a new method for the quantification of diabetic macular edema by volumetric analysis with the Heidelberg Retina Tomograph (HRT) scanning laser ophthalmoscope.

DESIGN

Topographic images of the macula were obtained in 25 consecutive patients who fitted the inclusion criteria. Twenty age-matched control subjects were randomly selected for a similar examination.

PARTICIPANTS

Twenty normal control eyes and 32 eyes of 25 patients with diabetes mellitus were studied.

INTERVENTION

Patients with diabetes were examined by HRT and slit-lamp biomicroscopy with a contact lens. On HRT, the volumes above reference plane bound by three consecutive circles centered at the fovea (diameter, 1, 2, and 3 mm) were measured. Measurements were repeated three times in a masked fashion, and the mean measurements were used for the analysis.

MAIN OUTCOME MEASURES

Visual acuity, macular edema, and volume above reference plane were measured.

RESULTS

There were 19 diabetic eyes with clinical macular edema (deemed positives) and 13 without edema (deemed negatives). Diabetic eyes with macular edema had statistically greater volumes above reference plane than did diabetic eyes without edema (P < 0.001) and greater than the control eyes (P < 0.001) for all three circles. There was no statistically significant difference between volumes measured in eyes without macular edema and control eyes (P = 0.42 for the 1-mm diameter circle; P = 0.72 for the 2-mm diameter circle; and P = 0.19 for the 3-mm diameter circle). For the two smallest circles only, the sensitivity of the HRT was 78.94%, and the specificity was 84.61%. None of the patients missed on the two smallest circles would have been positively identified on the 3-mm diameter circle.

CONCLUSION

The HRT can detect and quantify macular edema in diabetes by volumetric analysis with the method the authors have described. It is sufficient to measure the volumes above reference plane of two circles centered on the fovea and measuring 1 and 2 mm in diameter because the 3-mm diameter circle does not increase the system's sensitivity.

Indocyanine green angiography versus fluorescein angiography in the follow-up of choroidal melanomas treated with RU106/RH106

Indocyanine-green angiography and fluorescein angiography may complement each other in the follow-up and evaluation of choroidal melanomas treated with brachytherapy and may give a better understanding in the process of response of choroidal melanomas to brachytherapie. We did a retrospective study on 18 patients treated for this pathology.

Trilateral retinoblastoma. A report of five patients

BACKGROUND

Trilateral retinoblastoma is a well recognized, although rare, syndrome. Most of the reported cases have involved a family history of retinoblastoma (RB) and the disease is almost always fatal. The authors chose to investigate the cases of trilateral retinoblastoma occurring in the West Midlands, a region of the United Kingdom with an increasing incidence of bilateral sporadic RB.

METHODS

Five patients with trilateral retinoblastoma (including two were previously reported), diagnosed in 146 consecutive patients with RB in the West Midlands Health Authority Region between 1957 and 1994, are presented (an incidence of 3%). Their clinical presentation, treatment, and outcome are described.

RESULTS

There were 4 patients with pineoblastoma, only one of whom had a positive family history. The mean age at diagnosis of RB and 6 months, whereas the patients with pineoblastoma were diagnosed at a mean age of 2 years 8 months. The tumors were not evident on the initial computed tomography scans. One child presented with a calcified suprasellar mass 13 months before the bilateral sporadic RB was identified. Death occurred within 1 month of diagnosis of the intracranial tumor in 3 patients who did not receive any treatment. In the other 2 patients who were treated, death occurred at 15 months and 2 years 7 months, respectively, after diagnosis of intracranial tumor.

CONCLUSIONS

Early diagnosis with regular neuro-imaging and more aggressive treatment may improve prognosis in patients with RB and an intracranial tumor.

Radiation choroidal vasculopathy: an indocyanine green angiography study

An indocyanine green angiography (ICG-A) study of choroidal vasculature in the irradiated peritumoral zone in 16 eyes treated with 106Ru/106Rh brachytherapy for choroidal melanoma was performed between 4 and 72 months following treatment. The earliest changes observed were peritumoral atrophy of the retinal pigment epithelium and choriocapillaries. With time, the larger choroidal vessels progressively became non-perfused. There was only minimal staining of the smaller vessels. However, at 2 years or more after radiotherapy the larger choroidal vessels showed progressive vascular wall staining with ICG ('perivasculitis') associated with continuing closure. Previous histopathological studies of radiation damage to the choroid have demonstrated atrophy and occlusion of the vasculature but have shown no evidence of vasculitis. It is suggested that ICG staining of the choroidal vascular wall in radiation choroidopathy is due to radiation-induced endothelial cell loss or dysfunction rather than a true vasculitis. Subsequent progression results in vascular occlusion, and development of new clusters of abnormal choroidal vessels.

Indocyanine green angiography of choroidal tumors

BACKGROUND

Fluorescein angiography (FA) has been widely used in the diagnostic evaluation of choroidal tumors. Indocyanine green angiography (ICG-A), which permits better visualization of choroidal vasculature than FA, has been recently introduced into clinical practice. Only few reports exist on the ICG-A characteristics of choroidal tumors.

METHODS

The fluorescein and indocyanine green angiograms of 61 patients were assessed. These included 14 patients with choroidal nevi, 30 with malignant melanomas, 7 with suspected melanomas or atypical nevi, 5 with hemangiomas and 5 with metastases.

RESULTS

The outline of pigmented tumors was more accurate on ICG-A than on FA. Characteristic patterns were seen in all intra-ocular tumors with ICG-A, so it was possible to distinguish hemangiomas from malignant lesions. Characteristic features of malignant melanomas include abnormal vascular pattern and marginal late dye leakage. None of the benign lesions showed these features. In suspected melanomas, the presence of abnormal choroidal vascular patterns and/or late dye leakage on ICG-A may indicate malignancy.

CONCLUSION

The study suggests that ICG-A can yield additional information that is useful in differentiating amongst choroidal tumors. Better delineation of pigmented lesions with ICG-A allows more accurate treatment planning and follow-up.

Retinal and optic disc neovascularization in leukaemia

We report a case of chronic myeloid leukaemia initially presenting with a vitreous haemorrhage associated with bilateral retinal and optic disc neovascularization. The literature is briefly reviewed and the probable reasons for the observed microcirculatory disturbances are discussed.

Thirty years of retinoblastoma (1960-89): changing patterns of incidence

This study of a 30-year population-based dataset investigates further an earlier observation that the incidence of sporadic bilateral retinoblastoma appeared to be increasing in recent years in the West Midlands Health Authority Region (WMHAR). Stringent measures were applied to ensure complete ascertainment of all cases of retinoblastoma in children in the region, resulting in a total of 117 cases diagnosed during the period 1960-89 in the WMHAR. Hospital case notes were abstracted and follow-up data obtained. Incidence rates were calculated. The overall incidence remained constant over the 30-year period, but that of sporadic bilateral tumours increased, with a corresponding decline in familial cases. There was a statistically significant excess seen in Asian children.

The combined effect of diabetes and ionising radiation on the retinal vasculature of the rat

The clinical impression that pre-existing diabetes exacerbates radiation injury to the retinal vasculature was studied in STZ diabetic rats. Half of 2 groups of streptozotocin (STZ)-induced diabetic rats and 1 group of normal animals had their right eyes irradiated with 1000 cGy of 90 KVP x-rays. The prevalence of acellular capillaries in trypsin digests of the retinal vasculature was quantified for each of the 6 groups of animals at 6.5 months post-irradiation. The prevalence of acellular capillaries in both non-irradiated diabetic groups was significantly higher than in controls while the irradiated animals in each of the three main categories showed a statistically significant increase compared to their non-irradiated equivalents. However, the net increase in acellular capillaries following irradiation was much greater in rats with an 8 month term of pre-existing diabetes (180%) than in those which had only been diabetic for 3 months (36%). The results of this study suggest a synergistic relationship between pre-existing diabetes and ionising radiation in the development of retinal vasculopathy, and that the potentiation of the vascular damage is dependent on the duration of diabetes prior to radiation exposure.

Choroidoretinal neovascularisation following radon seed treatment of retinoblastoma in two patients

Two patients who developed localised radiation retinopathy many years after brachytherapy for retinoblastoma are described. In both patients extracapsular cataract extraction and YAG laser capsulotomy were followed by preretinal and vitreous haemorrhage and in one patient there was deterioration of existing radiation retinopathy with macular oedema. Premacular and vitreous haemorrhage occurred from focal, preretinal neovascular membranes which appeared to originate from residual choroidal vascular radicals. Laser photocoagulation was successful in ablating preretinal neovascular membranes and limiting the extent of macular oedema from incompetent retinal capillaries adjacent to the atrophic macular scars.

Late ultrastructural changes in the retina of the rat following low-dose X-irradiation

This study describes ultrastructural changes in the pigmented hooded Lister rat retina, 3-12 months following X-irradiation with single doses of between 200 and 2000 cGy. The extreme radiosensitivity of the photoreceptor cells was underlined by the continued manifestation of fine structural changes and cell death up to 6 months post-radiation in animals receiving doses above 500 cGy. The retinal pigment epithelial (RPE) cells were more radioresistant than photoreceptors and RPE cell loss was only observed at doses of more than 1500 cGy. One year after irradiation with 1500 cGy the retinal vasculature showed capillary occlusion with some evidence of recanalisation. Telangiectasia was observed in the large retinal veins. Although the inner retinal neurones and glial cells showed no evidence of direct radiation damage, the nerve fibre layer adjacent to occluded retinal vessels demonstrated ultrastructural evidence of ischaemic neuropathy and retinal oedema. At doses above 1500 cGy the choriocapillaris showed platelet aggregation and capillary loss.

Radiation retinopathy--clinical, histopathological, ultrastructural and experimental correlations

Clinical, pathological and experimental studies of radiation retinopathy confirm that the primary vascular event is endothelial cell loss and capillary closure. Pericytes are less susceptible, but typically atrophy as the capillaries become non-functional. The immediate effects of radiation reflect interphase and early mitotic death of injured endothelial cells, whereas later changes may be attributed to delayed mitotic death of compromised endothelial cells as they attempt division in the ordinary course of repair and replacement. Capillary occlusion leads to the formation of dilated capillary collaterals which may remain serviceable and competent for years. Microaneurysms develop in acellular and poorly supported capillaries, predominantly on the arterial side of the circulation and adjacent to regions of poorly perfused retina. Alterations in haemodynamics produce large telangiectatic-like channels which, typically develop a thick collagenous adventitia and may become fenestrated. Limited capillary regeneration occurs, usually evident as recanalisation of arterioles or venules by new capillaries. Vitreo-retinal neovascularisation may occur where retinal ischaemia is widespread. Radiation produces an exaggerated vasculopathy in patients with diabetes mellitus, and five month streptozotocin-induced diabetic rats develop a severe ischaemic retinopathy with vitreoretinal neovascularisation when exposed to 1500 cGy of radiation. Later photocoagulation is useful in containing or reversing microvascular incompetence and vasoproliferation in some patients with advanced radiation retinopathy.

Fluorescein angiographic features, natural course and treatment of radiation retinopathy

Fifteen patients who developed retinopathy following radiotherapy for cephalic tumours were studied by fluorescein angiography. Nine patients with unilateral or bilateral retinopathy had serial angiograms at six monthly or yearly intervals. Angiography revealed a wide range of retinal microvascular changes which were graded 1-4 according to the extent and degree of capillary malformation, incompetence and closure. All patients showed slow progression of retinopathy with remodelling of the affected microvasculature and increased capillary fallout and leakage to dye. The earliest retinopathic changes were capillary dilatation and closure and microaneurysm formation. Telangiectatic-like vessels were a feature of the established retinopathy and probably represented collateral channels which bordered sites of capillary occlusion. Two patients with progressive macular oedema and declining vision responded favourably to focal laser photocoagulation which returned a measure of competence to some residual dilated capillaries.

Orbital infiltration by eyelid skin carcinoma

This paper presents 5 patients seen in the Eye Clinic, Royal Victoria Hospital, Belfast with orbital infiltration of malignant eyelid tumours. The physical features and natural progression of the disease are described. The value of CT scans in determining the extent of the disease and patient management are described.

Cephalic radiation and retinal vasculopathy

The retinal vascular complications in patients receiving cephalic radiation for various lesions over a ten year period were reviewed. The incidence of retinopathy was 17% overall, but increased with proximity of the treatment site to the eye, being highest in irradiation of the eye/orbit (85.7%), paranasal sinuses (45.4%) and nasopharynx (36.4%). The risk of retinopathy increased significantly when the total dose of radiation exceeded 3000 cGy. The occlusive vasculopathy and capillary incompetence which were the most clinically important features of radiation retinopathy may be exacerbated by pre-existing diabetes. Radiation retinopathy has a long latency and may not be clinically detectable for eight years or more. Long follow-up times with sequential fundoscopy should increase early detection and optimise treatment with laser photocoagulation.

Early ultrastructural changes after low-dose X-irradiation in the retina of the rat

In this study Lister rats were given doses of X-rays ranging from 200-2,000 Rads to the retina of one eye, sacrificed at various time intervals between one hour and one month later and the irradiated eye processed for electron microscopy. The rod photoreceptor cells were by far the most radiosensitive cells in the retina, their outer segments showing distinctive membrane damage at one hour after 200 Rads of X-rays. Photoreceptor cell death was not seen at doses less than 1,000 Rads in the time period of the experiment. The retinal pigment epithelial (RPE) cells showed damage in the form of mitochondrial swelling but only in doses over 500 Rads. Retinal pigment epithelial cell loss did not occur under 2,000 Rads. The inner retinal neurones, glial elements and the retinal vasculature did not show any ill effects in the time period of this study.