Internal resection of posterior uveal melanomas

AIMS—To evaluate the safety and efficacy of internal resection in the treatment of malignant melanoma of the choroid.
METHODS—32 consecutive patients with histopathologically proved malignant choroidal melanomas were treated with internal resection. 29 of the 32 (90.6%) tumours were within 2 disc diameters of the optic nerve or fovea. The surgery was performed at two university centres by one of the authors. Follow up was between 1 and 85 months (mean 40.1 months).
RESULTS—Three patients developed distant metastases and died of malignant melanoma (metastatic and mortality rate 9.4%). In one case, distant metastases developed in association with an intraocular recurrence. There have been no other intraocular recurrences. The most common postoperative complication was vitreous haemorrhage, which occurred in 12 patients (37.5%); cataract occurred in eight eyes; and three patients developed retinal detachment postoperatively. Three of the operated eyes have been enucleated (9.4%); a total of four (12.5%) have lost light perception. 10 patients (31.2%) had visual acuities of 6/60 or better and 18 of 32 (56.3%) were between 6/120 and light perception.
CONCLUSION—These data suggest that the internal resection of posterior uveal melanomas is a reasonable globe saving management option. This treatment modality is particularly well suited to elevated tumours in close proximity to the optic nerve or fovea.

Keywords: choroidal melanoma; internal resection; malignant melanoma; posterior uveal melanoma     

Predictive factors for the development of rubeosis following proton beam radiotherapy for uveal melanoma

AIMS/BACKGROUND—Proton beam radiotherapy can effectively treat primary uveal melanomas of any size. Some patients, however, develop adverse late effects following treatment and the purpose of this study was to determine which factors give rise to a poor local outcome.
METHODS—The hospital records from a first cohort of 127 patients treated by protons from 1989 to 1992 were reviewed retrospectively. The presence of rubeosis was selected as a measure of significant ocular damage. Split file analysis was performed with 73 cases forming a test group with the remaining 54 cases acting as a validation group.
RESULTS—Large tumour size and the presence of retinal detachment were significant, independent risk factors for developing rubeosis for both the test and validation groups. These factors also predicted subsequent enucleation for uncontrolled ocular pain. Patients with tumours too large to plaque and with an associated retinal detachment had a 90% chance of developing rubeosis within 4 years of proton beam radiotherapy.
CONCLUSIONS—Patients with a uveal melanoma too large for plaque therapy and an associated retinal detachment run a very high risk of developing rubeosis after proton beam radiotherapy and one third of individuals developing rubeosis required enucleation for pain even if local tumour control was satisfactory.

     

Choroidal metastases and choroidal melanomas: comparison of ultrasonographic findings

AIMS—The purpose of the study was to analyse, whether the shape and the height to base ratio in B-scan ultrasonography are appropriate to differentiate choroidal melanomas from metastases.
METHODS—Between 1991 and 1996 16 eyes of 16 patients with choroidal metastases from breast carcinomas and 66 eyes of 66 patients with choroidal melanomas were evaluated ultrasonographically. The diagnosis of choroidal melanoma has been confirmed histologically in all eyes. Irradiated tumours were excluded from the study. Fisher's exact test and χ² test were used for statistical analysis.
RESULTS—Choroidal metastases demonstrated a significantly lower height to base ratio in B-scan (mean 0.18, SD 0.08) than melanomas (mean 0.6 (0.16); p < 0.001). A polygonal tumour surface was significantly more frequent in metastases (13 out of 16 metastases and in six out of 66 melanomas, p < 0.001). A choroidal excavation could be demonstrated in 38 melanomas and in no metastatic tumour (p < 0.001). The reflectivity was significantly higher in metastases than in melanomas.
CONCLUSION—The combined use of height to base ratio and reflectivity enables a highly significant discrimination between choroidal melanomas and metastases from the breast, thus probably constituting appropriate variables for the clinical differentiation.

Keywords: choroidal melanoma; choroidal metastasis; ultrasonography     

Retinal nerve fibre layer polarimetry: histological and clinical comparison

AIMS—To compare histological thickness of the retinal nerve fibre layer in the primate with retardation measurements obtained in vivo using the Mark II Nerve Fiber Analyzer (NFA, Laser Diagnostic Technologies, San Diego, USA).
METHODS—Scanning laser polarimetry was performed on both eyes of a healthy anaesthetised adult primate (Macaca mulatta). The retinal nerve fibre layer thickness was measured in the eye with the best polarimetry image. A nerve fibre layer thickness map was scaled and aligned to a retardation map to permit correlation of retardation and thickness measurements.
RESULTS—Retinal nerve fibre layer thickness measurements could be satisfactorily aligned with corresponding retardation values at 216 locations. The overall correlation coefficient for nerve fibre layer thickness and retardation was r = 0.70 (n = 216, p <0.001). Regional comparison showed the best correlation (r = 0.76, n = 45, p <0.001) occurred inferior to the optic disc. Less positive but still highly significant correlations were seen superiorly and temporally (r = 0.52, n = 26, p = 0.007 and r = 0.49, n = 86, p = <0.001 respectively), with the lowest correlation occurring at the nasal aspect of the disc (r  = 0.06, n  = 67, p = 0.64).
CONCLUSIONS—In the primate eye, retinal nerve fibre layer thickness shows a positive correlation with retardation measurements obtained with the nerve fibre analyser. However, since the correlation coefficient varied around the optic disc, further evaluation of the device is advised before its routine clinical use.

Keywords: nerve fibre layer; polarimetry; glaucoma; optic disc     

Echographic findings in uveal melanomas treated with the Leksell gamma knife

BACKGROUND/AIMS—Between June 1992 and July 1995, 29 uveal melanomas were treated radiosurgically with the Leksell gamma unit at the University of Graz. The aim of this retrospective study was to examine the pattern of regression and the extent and time period of the decrease in tumour size.
METHODS—The Leksell gamma knife, model B, was used. Patients were divided into three groups according to marginal dose: group 1: eight patients with a marginal dose >50 Gy, group 2: 15 patients with a marginal dose = 50 Gy, and group 3: six patients with a marginal dose = 45 Gy. For the retrospective study two groups were examined: group A, tumours <5 mm and group B, tumours 5 mm.
RESULTS—No significant correlation was found between tumour regression and the marginal dose. Tumour shrinkage depends on the pretreatment height. In the group of eight patients with an initial tumour prominence of less than 5 mm, no prominence was found after therapy. In the group of patients with an original tumour prominence of 5 mm and more, only two tumours formed a flat scar while a residual prominence was found in 18 patients. Increase in reflectivity combined with a decrease in size appears to be a good criterion for the effectiveness of the treatment. In five patients with tumours showing low reflectivity, over a longer period of time metastases were found. An enucleation was performed in two patients because of uncertain tumour regression and in one patient as a result of an increase in tumour size.
CONCLUSION—The pattern of echographic reflectivity and decrease in size is similar to brachytherapy and is one of the most important diagnostic variables for evaluation of tumour regression. An increase in reflectivity as well as a decrease in tumour size in the first 6-8 months can be considered a therapeutic success.

Keywords: gamma knife; uveal melanoma; echographic examination; reflectivity     

Effect of plasma colloid osmotic pressure on intraocular pressure during haemodialysis

BACKGROUND—In a previous case report, it was shown that an increase in plasma colloid osmotic pressure induced by the removal of fluid during haemodialysis was instrumental in decreasing intraocular pressure. The relation between changes in intraocular pressure, plasma osmolarity, plasma colloid osmotic pressure, and body weight before and after haemodialysis is evaluated.
METHODS—Intraocular pressure, plasma osmolarity, plasma colloid osmotic pressure, and body weight were evaluated before and after haemodialysis in 36 patients.
RESULTS—Intraocular pressure and plasma osmolarity both decreased significantly after haemodialysis (p<0.0001). Plasma colloid osmotic pressure increased significantly after haemodialysis (p<0.0001). Body weight decreased significantly because of the removal of fluid during haemodialysis (p<0.0001). No significant correlation was found between the change in intraocular pressure and that in plasma osmolarity (r=−0.206, p=0.2297), whereas the change in intraocular pressure was correlated with the change in plasma colloid osmotic pressure (r=−0.510, p=0.0012) and the change in body weight (r=0.534, p=0.0006). A significant correlation was found between the change in plasma colloid osmotic pressure and that in body weight (r=−0.756, p<0.0001).
CONCLUSION—The change in intraocular pressure was inversely correlated with the increase in plasma colloid osmotic pressure caused by the removal of fluid during haemodialysis.

Keywords: intraocular pressure; plasma colloid osmotic pressure; plasma osmolarity; haemodialysis     

Histopathological findings in human choroidal melanomas after transpupillary thermotherapy

AIMS—The effect of transpupillary thermotherapy (TTT) on human choroidal melanomas was investigated by means of histopathology.
METHODS—Before enucleation TTT was performed in 11 eyes with a xenon arc photocoagulator with a red filter or a diode laser at 810 nm. The exposure time was 1 minute; the estimated temperature at the top of the tumour was about 65°C.
RESULTS—Seven of 11 tumours developed necrosis to a maximum depth of 3.9 mm with a sharp demarcation between the necrotic and the viable part of the tumour. The depth correlated with penetration of heat into the tumour. Scattered small haemorrhages in the transitional zone between the necrotic and the viable part of the tumour were observed in three eyes but large haemorrhages were absent. Ocular media were not affected owing to the low rate of absorption of radiation at 810 nm. TTT did not cause significant scleral damage. Intrascleral tumour cells with a viable appearance were observed in one eye, where the tumour was almost totally necrotic.
CONCLUSION—Results show that TTT has potential as a conservative therapeutic treatment for choroidal melanomas.

     

Retinoinvasive malignant melanoma of the uvea

AIMS—To define a retinoinvasive phenotype of uveal melanoma based on an informative case and survey of literature.
METHODS—A 65-year-old woman developed a circumscribed mixed cell type melanoma of the ciliary body that was locally excised. After 6 years, secondary glaucoma evolved. Three years later a ring melanoma was diagnosed and the eye was enucleated. The histopathological material was analysed by immunohistochemistry.
RESULTS—A spindle cell type ring melanoma infiltrated the iris and ciliary body diffusely, and extended through the aqueous outflow channels and iridocyclectomy flap extrasclerally. The choroid was uninvolved. Instead, tumour cells spread to the vitreous and along the ciliary epithelium, adhered to the hyaloid face and retinal surface, and extensively invaded the neuroretina, the retrobulbar optic nerve, and perineural space. They were labelled for S-100 protein, vimentin, and in the neuroretina for cytokeratins 8 and 18. No evidence of systemic disease is evident 5 years after enucleation. Three identical tumours of the iris and ciliary body that extensively infiltrated the neuroretina and retrobulbar optic nerve were identified from previous literature.
CONCLUSION—Retinoinvasive melanoma is a rare but distinct phenotype of uveal melanoma, different from circumscribed and most diffuse melanomas that may erode the overlying retina and infiltrate the optic nerve but that do not invade non-adjacent retina. Retinoinvasive tumours tend to evolve from a ring melanoma and they grow slowly, which may favour emergence of tumour clones able to migrate, adhere to, and invade into the neuroretina, analogous to the metastatic cascade. Frequent secondary angle closure glaucoma may promote invasion into the optic nerve.

     

Topical anaesthesia with oxybuprocaine versus sub-Tenon's infiltration with 2% lignocaine for small incision cataract surgery

AIMS—To determine whether topical anaesthesia in small incision self-sealing phacoemulsification cataract surgery provides comparable anaesthesia to sub-Tenon's infiltration.
METHODS—Thirty five patients undergoing small incision self-sealing phacoemulsification cataract surgery were allocated randomly to receive topical anaesthesia with 0.4% oxybuprocaine or sub-Tenon's infiltration with 2% lignocaine. Pain experienced during the operation was assessed by asking the patient to score on a visual analogue graphic pain score chart.
RESULTS—The median pain score for the topical group (3) was significantly higher than that of the sub-Tenon's group (0) (p = 0.004).
CONCLUSION—Sub-Tenon's infiltration is superior to topical anaesthesia in ensuring patient comfort during small incision scleral tunnel self-sealing phacoemulsification cataract surgery.

     

Expression patterns of cyclin D1 and related proteins regulating G1-S phase transition in uveal melanoma and retinoblastoma

BACKGROUND/AIMS—A checkpoint mechanism in late G1, whose regulation via loss of retinoblastoma protein (pRB) or p16, or overexpression of cyclin D1 or cyclin dependent kinase 4 (CDK4), has been proposed to constitute a common pathway to malignancy. The aims of this study were (a) to compare markers of cell cycle G1-S phase transition in an intraocular tumour with known pRB deficiency (retinoblastoma) and compare it with one with an apparently functional pRB (uveal melanoma); (b) to determine if one of these markers may have a role in the pathogenesis of uveal melanoma; and (c) to determine if there is a difference in cell cycle marker expression following treatment of uveal melanoma and retinoblastoma.
METHODS—90 eyes were enucleated from 89 patients for retinoblastoma (n=24) or for choroidal or ciliary body melanoma (n=66). Conventional paraffin sections were assessed for cell type and degree of differentiation. Additional slides were investigated applying standard immunohistochemical methods with antibodies specific for cyclin D1 protein, pRB, p53, p21, p16, BCL-2, and MIB-1.
RESULTS—Cyclin D1 protein and pRB were negative in retinoblastoma using the applied antibodies. In contrast, cyclin D1 protein expression was observed in 65% of uveal melanomas; a positive correlation between cyclin D1 cell positivity and tumour cell type, location, growth fraction, as well as with pRB positivity was observed. p53, p21, and p16 could be demonstrated in both tumours. An inverse relation between p53 and p21 expression was demonstrated in most choroidal melanomas and in some retinoblastomas. Apart from a decrease in the growth fractions of the tumours as determined by MIB-1, a significant difference in the expression of G1-S phase transition markers in vital areas of uveal melanoma and retinoblastoma following treatment with radiotherapy and/or chemotherapy was not observed.
CONCLUSION—Retinoblastomas and uveal melanomas, two tumours of differing pRB status, differ also in their immunohistochemical pattern for markers of the G1-S phase transition of the cell cycle. The results of the present study support the concept of (a) an autoregulatory loop between pRB and cyclin D1 in tumours with a functional pRB and the disruption of this loop in the presence of pRB mutation, as well as (b) a checkpoint mechanism in late G1, whose regulation via loss of p16 or pRB, or overexpression of cyclin D1 constitutes a common pathway to malignancy. Further, the results raise the possibility of cyclin D1 overexpression having a role in the pathogenesis of uveal melanoma.

Keywords: cyclin D1; retinoblastoma protein; antigens; antibodies; bipolar cells; uveal melanoma; retinoblastoma     

Long-term results of proton beam irradiated uveal melanomas

The first 128 consecutive patients with uveal melanomas treated with proton beam irradiation were studied in order to evaluate survival and visual acuity status of patients with relatively long-term follow-up. The median follow-up was 5.4 years, and no patient was lost to follow-up. All tumors showed regression. The most recent visual acuity was 20/40 or better in 35% and 20/100 or better in 58%. Eight eyes were enucleated because of complications. Metastasis developed in 26 patients (20.5%) from 3 months to 7 years after treatment. Results indicate that proton irradiation is quite successful for achieving local control of uveal melanomas. A large proportion of the treated eyes maintained useful vision. Five-year follow-up data indicate that proton irradiation has no deleterious effect on the likelihood of the development of metastasis.     

Altered retrobulbar vascular reactivity in early diabetic retinopathy

AIM/BACKGROUND—In diabetic eye disease the factors leading to compromised circulation and the resulting loss of visual function are poorly understood. Although retinal circulation has been widely investigated, it accounts for only a fraction of total eye blood flow. Blood flow was investigated in the larger vessels feeding the eye in patients with early diabetic retinopathy.
METHODS—Eleven patients with early diabetes with minimal or no retinopathy and 11 healthy controls were evaluated for retrobulbar blood flow velocity using colour Doppler imaging for the ophthalmic and central retinal arteries. Patients and subjects were tested while breathing room air and again under conditions of isocapnic hyperoxia.
RESULTS—Hyperoxia induced a significant change in the central retinal artery end diastolic velocity (EDV) (p = 0.008) and resistance index (RI) (p = 0.032) in normal subjects, but not in diabetic patients. Consequently, during hyperoxia, the diabetic patients were significantly higher for EDV (p = 0.006) and significantly lower for RI (p = 0.002) compared with normal controls. Hyperoxia caused no significant change in either group in the ophthalmic artery; nevertheless, under isocapnic hyperoxia conditions the diabetic patients had lower peak systolic velocity (p = 0.05) and lower RI (p = 0.05) than normal subjects.
CONCLUSIONS—Imposition of isocapnic hyperoxia produces significant differences in the ophthalmic and central retinal artery blood flow velocities in diabetic patients with early disease when compared with normal subjects. These results demonstrate that diabetic patients with minimal or no retinopathy suffer from irregular ocular vascular function in the major vessels feeding the eye.

     

Does cryotherapy before drainage increase the risk of intraocular haemorrhage and affect outcome?. A prospective,randomised, controlled study using a needle drainage technique and sustained ocular compression

AIMS/BACKGROUND—A prospective, randomised, controlled clinical trial was conducted to investigate the effect of performing cryotherapy before drainage of subretinal fluid (SRF) on the incidence of intraocular haemorrhage (IOH) in the management of retinal detachment.
METHODS—Eighty eyes of 80 patients with rhegmatogenous retinal detachment requiring SRF drainage were recruited. Thirty four cases were randomised to receive drainage before cryotherapy (drainage, air injection, cryotherapy, and explant = DACE group) while 46 cases had drainage after cryotherapy (cryotherapy, drainage, air injection, and explant = CDAE group). All cases had trans-scleral drainage of SRF using a 27 gauge hypodermic needle combined with prolonged, intraocular hypertension.
RESULTS—There was a low incidence of IOH associated with drainage in both groups with no statistically significant difference between the groups (DACE group = 2.9%; CDAE group = 4.3%; p = 0.43). There was no significant difference between the groups in the rate of anatomical success with a single operation (DACE group = 82.4%; CDAE group = 86.9%; p = 0.38). There was no significant difference between the groups in the visual outcome. An improvement of two Snellen lines or more occurred in 52.9% of the DACE group and in 56.5% of the CDAE group (p = 0.93).
CONCLUSION—It was concluded that the surgical sequence of applying cryotherapy before drainage of SRF can be safely and effectively performed. The sequences CDAE and CDE, when air injection is not required, along with DACE should all be part of the surgical repertoire for the management of retinal detachments.

     

Echographic measurements of the retrobulbar optic nerve in normal and glaucomatous eyes

AIM—A study was designed to investigate whether measurements of the optic nerve diameter (OND) and cross sectional area (ONCSA), as measured by B-scan ultrasonography, are altered in glaucoma. The reproducibility and test-retest variability of echographic estimates of retrobulbar optic nerve dimensions was also tested.
METHODS—One eye of 49 glaucoma patients and 90 control subjects underwent five repeated echographic measurements of the maximal interpial diameter and cross sectional area of the orbital optic nerve on two separate occasions. All measurements were taken by one experienced ultrasonographer.
RESULTS—Mean optic nerve diameter (SD) for the control group was 2.86 (0.46) mm, and was independent of height (multiple regression analysis: p = 0.21), axial length (p = 0.74), spherical equivalent (p = 0.97), sex (ANOVA: p=0.36), or race (p=0.14), but was inversely related to age (p = 0.01). Reproducibility of OND readings in control subjects was 0.149 mm (coefficient of repeatability). Test-retest variability of interpial diameter was −0.02 (0.29) mm. Mean interpial diameter of the optic nerve was significantly smaller among glaucomatous eyes (2.58 (0.501) mm) than controls (Mann-Whitney U test: p < 0.0001). Glaucomatous optic nerves also had a significantly smaller cross sectional area (6.68 (2.58) mm²) than those of healthy volunteers (8.25 (1.67) mm²) (p = 0.004).
CONCLUSION—Echographic measurements of the orbital optic nerve are highly reproducible and not subject to clinically meaningful test-retest variability. Optic nerve interpial diameter and cross sectional area are reduced in glaucomatous eyes, reflecting nerve fibre loss. This technique may be useful in distinguishing between normal and glaucomatous eyes where optic disc morphometry is inconclusive or impossible as a result of opaque media.

Keywords: glaucoma; optic nerve; ultrasound     

Brain natriuretic peptide: identification of a second natriuretic peptide in human aqueous humour

AIMS/BACKGROUND—To measure aqueous humour levels of brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP) in humans. To compare peptide levels in glaucomatous and control eyes to test the hypothesis that these peptides are increased in glaucoma. BNP and ANP are cyclic endopeptides whose principal biological effects are natriuresis and vasodilatation. Experimental glaucoma in animal models results in elevated aqueous ANP. Intravenous ANP administration in both animals and humans causes lowering of intraocular pressure (IOP). There are equivocal data to support a role for ANP in IOP regulation in human eyes. There are as yet no published data on BNP in human aqueous humour.
METHOD—This was a case-control study. Cases were primary open angle, pseudoexfoliation, and mixed mechanism glaucoma eyes undergoing trabeculectomy. Controls were cataract extraction eyes. There were 47 trabeculectomy eyes (44 patients) and 47 cataract extraction eyes (46 patients) matched for age, sex, race, systemic medications, and type of anaesthetic. 100-200 µl of aqueous humour were aspirated by paracentesis as the first step in the surgical procedure. Peptide levels were later measured by radioimmunoassay.
RESULTS—The presence of BNP and ANP in human aqueous humour was confirmed. BNP was present in higher concentrations than ANP. BNP levels tended to be greater in control eyes—glaucoma median 56.5 (range 0-3526.5) pg/ml versus control median 65.16 (range 0-1788) pg/ml (Wilcoxon signed rank test p = 0.78). ANP levels tended to be greater in glaucoma eyes than in controls: glaucoma median 3 (range 0-68.5) pg/ml versus control median 0 (range 0-60) pg/ml (Wilcoxon signed rank test p = 0.82). ANP and BNP were log linearly related in both groups (r glaucoma group = 0.961, r control group = 0.894).
CONCLUSION—This is the first report of BNP and ANP in human aqueous humour. Peptide levels did not differ significantly between glaucoma and cataract extraction eyes. A linear relation between log BNP and ANP was found. Further studies are required to clarify the role of these peptides in aqueous humour production and IOP regulation.

Keywords: brain natriuretic peptide; aqueous natriuretic peptide; aqueous humour; glaucoma     

Effect of lodoxamide and disodium cromoglycate on tear eosinophil cationic protein in vernal keratoconjunctivitis

AIM—To validate the use of tear eosinophil cationic protein (ECP) as a marker for eosinophil activation, and its pharmacological modulation, in addition to evaluating the efficacy of lodoxamide and sodium cromoglycate in the treatment of vernal keratoconjunctivitis (VKC).
METHODS—Tears were collected from 30 patients affected by active mild to moderate VKC before and after therapy with disodium cromoglycate 4% (DSCG) (n=15) or lodoxamide 0.1% (n=15) for 10 days. Tear cytology and ECP measurement were performed, and ocular signs and symptoms evaluated.
RESULTS—While statistically significant changes did not occur after DSCG therapy, mean tear ECP increased from 343 (SD 363) µg/l to 571 (777) µg/l due to marked elevation in six eyes. The clinical score in DSCG eyes did not improve. After lodoxamide therapy, both clinical signs and symptoms, and tear ECP levels (560 (756) µg/l to 241 (376) µg/l) decreased significantly (p<0.0001 and p<0.01, respectively). Compared with DSCG treatment, lodoxamide was more effective in reducing signs and symptoms (p<0.005). ECP levels were significantly correlated with signs, symptoms, corneal involvement, and number of eosinophils in tears (p<0.0001).
CONCLUSIONS—In patients with VKC, lodoxamide significantly reduced ECP tear levels, and thus, eosinophil activation, and was more effective than DSCG in reducing clinical signs and symptoms.

     

A clinical study of radiation cataract formation in adult life following γ irradiation of the lens in early childhood

AIMS—To analyse long term effects on the lens of radium irradiation during infancy.
METHODS—An infant cohort (n = 20, median age 6 months) treated for skin haemangioma with one or two radium-226 needles located at or within the orbital rim was examined 30 to 45 years after γ radiation. Detailed information about the treatment procedure was available for all cases. Subcapsular opacities were graded semiquantitatively according to a scale based on extent and density of the opacities.
RESULTS—A high prevalence of light to moderate posterior, subcapsular, and cortical cataract formation was found in the lenses on the treated side irradiated with a mean dose ranging from approximately 1 to 8 Gy. The cataract formation increased as a function of dose. The presence of subcapsular punctate opacities and vacuoles in the lenses on the untreated side receiving irradiation of an estimated dose varying around 0.1 Gy indicates a higher sensitivity than expected.
CONCLUSION—The growing lens during infancy is sensitive to radium irradiation at doses lower than those previously stated. The eye lens seems suitable for studies of effects of low dose radiation since damaged cells are retained in the lens for a lifetime.

     

Oxygen free radical damage in the cornea after excimer laser therapy

AIMS/BACKGROUND—To evaluate the extent of oxygen radical damage in the cornea after excimer laser ablation.
METHODS—The 193 nm argon fluoride excimer laser was programmed for an average fluence of 150 mJ/cm², with a firing rate of 5 Hz and an ablation zone diameter of 6 mm. Phototherapeutic keratectomy was performed to remove 30 µm of epithelium and 50 µm of stroma from the corneas of New Zealand white rabbits. Oxidative tissue damage after laser was determined by measuring oxidised lipids (conjugated dienes and ketodienes) in corneal lipid extracts, and by fast blue B staining to localise the lipid peroxide in the tissue.
RESULTS—Conjugated diene levels were 3.73 (SD 0.56) nmol per hemicornea in ablated corneas and 1.99 (0.33) nmol per hemicornea in normal corneas (p = 0.0044). Ketodiene levels were 2.72 (0.38) nmol per hemicornea in treated corneas and 0.91 (0.12) nmol per hemicornea in normal corneas (p < 0.001). Fast blue B staining disclosed that the tissue damage occurred primarily on the surface of the ablated cornea.
CONCLUSION—The presence of lipid peroxidation in the superficial corneal stroma in excimer laser treated corneas was demonstrated. This lipid peroxidation could be from oxygen free radicals generated by the infiltrating polymorphonuclear cells at the site of tissue damage.

     

Role of chemotherapy alone or in combination with hyperthermia in the primary treatment of intraocular retinoblastoma: preliminary results

BACKGROUND—The efficacy of the etoposide-carboplatin combination in extraocular retinoblastoma is well known. This drug combination is therefore used in intraocular retinoblastoma, as primary reduction chemotherapy, before local treatment. The use of carboplatin in combination with diode laser hyperthermia as local treatment (thermochemotherapy) has been recently described as a conservative approach avoiding external beam radiotherapy in posterior pole tumours.
METHODS—All patients were reviewed, who were treated for retinoblastoma at the Institut Curie between June 1994 and October 1995, in whom treatment included either reduction chemotherapy or thermochemotherapy or both modalities successively. 23 patients presenting with unilateral (three) or bilateral (20) intraocular retinoblastoma received neoadjuvant chemotherapy consisting of two courses of etoposide 150 mg/m²/day and carboplatin 200 mg/m²/day for 3 days. 15 patients (17 eyes), eight of whom had already received neoadjuvant chemotherapy, were treated by thermochemotherapy.
RESULTS—Neoadjuvant chemotherapy: overall, seven eyes in seven patients could be treated conservatively, avoiding external beam irradiation, with a median follow up of 14 months. Thermochemotherapy: external beam irradiation was avoided for 14 of the 17 eyes treated.
CONCLUSION—Integration of neoadjuvant chemotherapy and combined treatment with carboplatin and diode laser, into the therapeutic armamentarium for retinoblastoma allows use of more aggressive treatments such as enucleation and external beam radiation.

Keywords: retinoblastoma; chemotherapy; thermochemotherapy     

Peroperative microbial contamination of anterior chamber aspirates during extracapsular cataract extraction and phacoemulsification

BACKGROUND—The normal conjunctival flora is one of the main sources of intraocular contamination during cataract surgery. The theory that the positive anterior chamber (AC) pressure during phacoemulsification (phaco), and the smaller wound utilised, might reduce the rate of contamination was studied.
METHODS—The peroperative AC aspirates of 210 consecutive patients undergoing cataract surgery were assessed. In group 1, 100 patients underwent a standard extracapsular cataract extraction (ECCE). In group 2, 110 patients underwent phacoemulsification of the crystalline lens through a scleral tunnel. AC aspirates from the Simcoe irrigation/aspiration cannula (group 1) and phaco probe (group 2) were collected and microbiological studies performed after direct and enrichment cultures.
RESULTS—There were 29 (29%) positives in the ECCE group compared with 22 (20%) positive cultures from AC aspirates in the phaco group. Coagulase negative staphylococcus (CNS) was the commonest contaminant in both groups.
CONCLUSION—Although there was a higher rate of AC contamination during ECCE, the difference was not statistically significant (p> 0.10, χ²=2.31).