Iatrogenic retinal traumas in ophthalmic surgery

BACKGROUND: To describe the main retinal iatrogenic traumas possibly related to ophthalmic surgery and the precautions to be adopted to avoid them. METHODS: The article reviews the main peer-reviewed literature concerning retinal injuries caused by surgically related maneuvers. Safety measures alleged to inhibit any possible iatrogenic damage are also evaluated. RESULTS: Photochemical damage of the retina, retinal complications after strabismus surgery, retinal complications related to local anesthesia for ophthalmic surgery, retinal damage during cataract surgery and retinal damage during vitreoretinal surgery are the most common iatrogenic retinal injuries. Their incidence is related to risk factors peculiar to each condition. CONCLUSIONS: Ophthalmic surgeons are aware that there are a number of circumstances in which several undesirable retinal iatrogenic injuries might occur, sometimes with serious consequences. This is why surgeons should take every precaution at each surgical step to avoid any possible retinal iatrogenic damage.     

枸杞子提取物对光诱导视网膜损伤的保护作用

目的　探索枸杞子提取物对人视网膜色素上皮（ARPE-19）细胞及C57BL/6J小鼠视网膜光诱导损伤的保护作用。方法　ARPE-19细胞分为正常细胞对照组,光诱导细胞损伤组,细胞低、中、高剂量组（0.1 g·L^-1、0.5 g·L^-1、1.0 g·L^-1枸杞子提取物+光诱导细胞损伤）,测定各组细胞活力以及细胞内活性氧（ROS）含量的变化。40只C57BL/6J小鼠随机分为正常动物对照组,光诱导动物损伤组,动物低、中、高剂量组（280 mg·kg^-1、370 mg·kg^-1、460 mg·kg^-1枸杞子提取物+光诱导动物损伤组）,每组8只。各剂量枸杞子提取物干预组小鼠在6周龄开始给予枸杞子提取物灌胃,8周后再给予10 000 lux光照射24 h;光照结束后ERG评估各组小鼠视网膜功能,OCT检测视网膜外核层（ONL）厚度,FFA检测视网膜血管渗漏情况,HE染色后对视网膜ONL细胞进行计数,同时检测血清中丙二醛（MDA）含量和超氧化物歧化酶（SOD）、谷胱甘肽过氧化物酶（GSH-Px）活性。结果　光诱导细胞损伤组ARPE-19细胞活力下降为正常细胞对照组的61.88%,细胞内ROS含量为正常细胞对照组的1.52倍;细胞低、中、高剂量组ARPE-19细胞活力较光诱导细胞损伤组均明显上升,细胞内ROS含量均明显下降,并均呈剂量依赖性（均为P＜0.05）。与动物对照组相比,光诱导动物损伤组小鼠ERG暗适应a波、b波振幅和明适应b波振幅均明显下降,动物低、中、高剂量组各波的振幅均得到不同程度改善。光诱导动物损伤组小鼠视网膜出现萎缩灶、血管渗漏和血管末端成珠样结构,视网膜ONL厚度变薄,为（52.18±4.23) μm,ONL每列细胞数明显减少,为（17.63±1.30）个;动物低、中、高剂量组小鼠视网膜病理改变及视网膜ONL厚度与ONL每列细胞数均得到不同程度改善,尤其动物高剂量组改善最为明显,ONL厚度为（59.72±2.76）μm, ONL每列细胞数为（20.00±1.51）个,与光诱导动物损伤组相比差异均有统计学意义（P=0.007、0.004）。相对于光诱导动物损伤组,动物低、中、高剂量组小鼠血清SOD、GSH-Px活性均明显提高,MDA含量均明显下降,且均呈剂量依赖性（均为P＜0.05）。结论　枸杞子提取物可以一定程度上保护视网膜免受光损伤。     

Possible damage to the eye caused by light from ophthalmologic equipment

Motivated by numerous findings of the damaging effect of intense light levels on the fundus we measured the spectral radiation of several ophthalmic illuminations and used it to calculate from it the spectral retinal irradiance. To evaluate the thermal hazard, we calculated the resulting temperature rise at the fundus. A measure for biological damage is the percentage of denaturated molecules, which is related to the temperature rise and its duration (essentially identical to the duration of illumination) by the so-called Arrhenius-integral. We used this measure to compare any illumination with experimentally evaluated threshold values for thermal damage. To evaluate the photochemical hazard we compared the spectral retinal irradiance with threshold values for photochemical induced lesions. Furthermore the illuminations were correlated with safety-guidelines likewise distinguishing between thermal and photochemical hazard. Under adverse conditions operation microscopes can present a thermal hazard to the patient's eye. Other ophthalmic illuminations are of less concern in this respect. A similar estimation applies to hazard from photochemical effects. The photochemical hazard can be diminished essentially by reducing the short-wavelength bluelight. Qualitatively, maximal permissible exposures according to safety guidelines are consistent with our thermal calculations as well as with photochemical hazard evaluation by comparing spectral retinal light levels with threshold irradiance for photochemical induced lesions. However, since quantitatively safety guidelines estimate the thermal hazard very conservatively, many common ophthalmic illuminations exceed the exposure limits, in some cases even drastically.     

Updating on intraoperative light-induced retinal injury

We are presenting the state of knowledge concerning intraoperative light-induced retinal injury, considered to be a combination of photic retinopathy and retinal photocoagulation. It may arise from retinal light exposure to the operating microscope or to the fiberoptic endoilluminator. Ultraviolet and short-wavelength visible light are more dangerous than longer wavelength light. Many risk factors may facilitate the onset of this iatrogenic disease following surgery. Many aspects of the retinal damage are still poorly understood. Many mild light-induced retinal injuries probably remain undiagnosed in routine postoperative examination. Current appropriate light filters are not the definitive solution. Appropriate precautions should be taken during both anterior segment and vitreoretinal surgery.     

Auckland proliferative diabetic vitrectomy fellow eye study

BACKGROUND: To review medical and ophthalmic findings of primary diabetic vitrectomy patients to examine indices important in progression to fellow eye surgery. METHODS: A retrospective analysis was undertaken of all diabetic patients undergoing vitreoretinal surgery at Auckland Public Hospital between January 1992 and July 1996. Kaplan-Meier survival analysis was performed along with univariate and multivariate (Cox Proportional Hazards) data analysis. RESULTS: One hundred and fourteen primary diabetic vitrectomy cases were reviewed with mean follow-up duration of 4 years. Thirty-eight per cent (n = 43) of the study group underwent fellow eye surgery at a mean time of 1.6 years after first eye surgery. Fourteen patients were already blind in the fellow eye at baseline, and five patients refused second eye surgery on intention to treat. Thus there were 62 (54%) patients with severe (surgical threshold) fellow eye disease diagnosed within the follow-up period. The presence of either tractional retinal detachment or combined rhegmatogenous/tractional retinal detachment but without vitreous haemorrhage in the presenting eye was, in this series, a risk factor for fellow eye surgery (OR 5.56; 95% CI 1.96-15.8). Maori and Pacific Islander ethnicity was significantly associated with traction retinal detachment (OR 2.23; 95% CI 1.05-4.7). At data analysis 57% (n = 60) of the study patients had died. The mean time to death was 4.3 years, with 84% of these patients having evidence of renal disease at the time of their first eye surgery. Good visual function in at least one eye was maintained in many patients. CONCLUSIONS: A substantial proportion of diabetic vitrectomy patients require fellow eye surgery. Absence of vitreous haemorrhage in the presenting eye (i.e. tractional or combined rhegmatogenous/tractional retinal detachments but without vitreous haemorrhage) was predictive of need for fellow eye surgery. The need for diabetic vitrectomy correlates with poor survival in this study population.     

Retinal dialysis: are we missing diagnostic opportunities?

AIMS: To review medical records of those patients managed by our department for retinal dialysis, and establish whether the initial assessment had been adequate to make the diagnosis. That is, to establish if an adequate initial assessment had been performed that would reasonably exclude the likelihood of retinal dialysis and other trauma-related sequelae such as angle recession. METHODS: A retrospective review was made of all patients managed for retinal dialysis at Sussex Eye Hospital between 20 March 1997 and 20 September 2002 (66 months). In addition to general demographic data, surgical management and outcome, patient files were reviewed for history of trauma, prior ophthalmic review, and whether such review included documentation of peripheral retinal examination and gonioscopy. RESULTS: A total of 580 primary procedures were performed for retinal detachment during the review period, of which 32 eyes of 29 patients underwent surgery for retinal dialysis (6%). There were 21 male and eight female patients, with a history of trauma obtained in 55% (17 eyes, 16 patients). Of the 16 patients with prior trauma, nine had undergone prior ophthalmic review at the time or soon after their trauma; however, only 2 (22%) had documented evidence of indented peripheral retinal examination. Only one (3%) patient in the whole series had documented gonioscopy. CONCLUSIONS: Patients with history of trauma often present at the time or soon after their injury (eg hyphaema, orbital fractures). Thus, an opportunity exists to screen patients for known sequelae of trauma such as retinal dialysis and angle recession. It was disappointing to learn that this opportunity was not always being utilized, with some patients consequently developing macula-off retinal detachments and potential for reduced visual outcome.     

Photic maculopathy after extracapsular cataract surgery. A prospective study.

Photic retinal injuries have been described after surgical exposure to the intense illumination systems of operating microscopes. The overall incidence of such injuries has been postulated at less than 10%. The authors prospectively studied 43 consecutive patients to determine the incidence of photic macular injuries during cataract surgery. Patients underwent complete ophthalmic examinations, fundus photography, and oral fluorography before and after surgery. Photic macular injuries developed in 12 of 43 eyes (28%) as a result of intraocular surgery. This incidence is much higher than previous estimates. The association with possible risk factors, cystoid macular edema, and the effect of these injuries on final visual acuity are discussed.     

Retinal phototoxicity from the operating microscope. The role of inspired oxygen

The effect of the inspired oxygen concentration (FIO2) on the production of retinal phototoxicity by the operating microscope was studied in phakic rhesus monkeys. One eye of each monkey was exposed to light under conditions of 99% FIO2, and the other eye was exposed under 21% oxygen (O2). Three of four locations on each retina were exposed to light for durations varying from 1 1/2 to 20 minutes per exposure. Fundus photographs and fluorescein angiograms were obtained 24 to 72 hours after exposure. Animals were euthanatized for analysis of retinal histopathology at intervals from 2 weeks to 8 months after light exposure. Retinal phototoxic lesions were produced after an average of 5 minutes of light exposure under both 21 and 99% O2. O2 potentiated the light damage both clinically and histologically. Under both conditions, lesion size was directly related to the duration of light exposure (P less than 0.005). Lesions near threshold produced with 99% FIO2 were 1.6 to 6.9 (mean, 2.9) times larger than the corresponding lesions formed with 21% FIO2. Histologic damage was likewise more severe in lesions produced under high O2 conditions. Retinal repair occurred in lesions produced under high and low O2 conditions. Photoreceptor regeneration was nearly complete by 18 weeks, whereas retinal pigment epithelial (RPE) recovery lagged up to 1 1/2 months. The results of this study have important implications for clinical practice: the operating microscope can produce retinal phototoxicity rapidly, and O2 administered during ophthalmic procedures may potentiate the damage if appropriate precautions are not taken.     

Reactivity of white blood cell flux to hyperoxia in patients infected with human immunodeficiency virus

Purpose: The aetiology of the apparently vasoocclusive phenomena in human immunodeficiency virus (HIV)‐related retinopathy is not well understood. Several hypotheses, including infectious damage of the retinal vasculature and altered retinal haemodynamics, have been postulated. Direct measurement of oxygen tension in the retina is not possible in vivo and indirect methods have to be employed. The objective of this study was to investigate the retinal vascular response to 100% oxygen breathing in patients with HIV. Methods: Twelve patients infected with HIV and 12 healthy individuals, matched for age, sex and smoking habits, were studied in an open study using the blue‐field entoptic technique for the measurement of retinal white blood cell (WBC) flux. Reactivity in retinal blood flow during 100% O₂ breathing over 15 min was measured and expressed as percentage change over baseline. Results: WBC velocity during oxygen inhalation decreased over baseline by 9.0 ± 5.8% in HIV‐infected patients and by 18.6 ± 5.4% in healthy participants (p < 0.04 between groups, anova ). The decrease in WBC velocity was paralleled by a decrease in WBC density. This decrease tended to be more pronounced in healthy participants (13.6 ± 7.9%) than in HIV‐infected patients (8.0 ± 10.8%), but the difference was not statistically significant (p = 0.1 between groups, anova ). WBC flux decrease was 16.2 ± 11.4% in HIV‐infected patients and 29.5 ± 9.5% in the control group and was significant between groups (p = 0.007 between groups, anova ). Conclusion: Our results indicate a reduced reactivity of WBC flux to systemic hyperoxia in patients with HIV. Whether abnormal retinal haemodynamics in HIV‐infected persons contributes to the pathogenesis of HIV‐related microvascular diseases or is a consequence of the structural changes associated with the disease is unknown.     

视网膜光损伤机制的研究进展

视网膜是一种高度专业化的组织,具有独特的结构及适应性,在所有不同类型的视网膜细胞中保持动态平衡对于维持视力至关重要。视网膜可能会暴露在各种环境损伤中,如光诱导的损伤,在进化过程中,视网膜细胞对各种损伤产生了适应性反应,这些反应共同恢复了细胞的动态平衡,并增加了组织对进一步损伤的抵抗力。然而过度光照则会导致视网膜组织内光感受器细胞、视网膜神经节细胞(RGC)、视网膜神经胶质细胞及视网膜色素上皮细胞(RPE)发生一系列病理改变,包括线粒体内活性氧(ROS)和Ca²⁺浓度增加、细胞凋亡、内质网应激、细胞自噬和炎症等,从而导致视网膜发生不可逆损伤。本文将对视网膜光损伤的发病机制和相关研究进展进行详细阐述,为未来防治视网膜光损伤提供研究方向。     

Effects of vitamin e, pentoxifylline and aprotinin on light-induced retinal injury

PURPOSE: A considerable amount of clinical and experimental evidence exists suggesting the involvement of reactive oxygen species (ROS) in the etiology of light-induced retinal injury. The aim of this study was to investigate the protective role of vitamin E, pentoxifylline (PTX) and aprotinin against light-induced retinal injury in guinea pigs. METHODS: Thirty adult male guinea pigs were divided into 5 groups of 6 animals each. The first group was used as control. The guinea pigs were kept in cyclic light for 2 weeks before the experiments. The animals were maintained in 12-hour light-dark cycles, before and after exposure to intense white fluorescent light, for as long as 12 h and then returned to cyclic light. Groups 3-5 received intraperitoneal injections of vitamin E, PTX and aprotinin, respectively. One eye of each animal was selected for histopathological evaluation and the other for biochemical assay. Retinal malondialdehyde (MDA) levels and the thickness of the outer nuclear layers were measured. RESULTS: The compounds had the following relationships: vitamin E more than PTX more than aprotinin in preventing light-induced retinal damage. All 3 gave significant protection against the formation of MDA. Retinas of all 3 treatment groups had been protected from light-induced injury. CONCLUSION: The intraperitoneal vitamin E, PTX and aprotinin supplementations may strengthen the antioxidant defense system because of decreased ROS, and these agents may play a role in treating light-induced retinal injury.     

Retinal nerve fiber layer analysis and evaluation of eye blood flow in patients with glaucoma

PURPOSE: The aim of this research was to evaluate the changes of blood flow velocity in ocular arteries (ophthalmic artery, central retinal artery and short posterior ciliary arteries) and the amount of ocular nerve fibers in patients with primary open angle glaucoma (POAG) and normal tension glaucoma (NTG). MATERIAL AND METHOD: The research was done on 17 patients with diagnosed POAG and 13 patients with NTG. No ocular surgery was performed on any of these patients prior to our examinations. The blood flow measurements were made with ACUSON Color Doppler USG 128*P10 type with 7.5 MHz sector phased probe. Parameters of diastolic velocity (Vr), systolic flow velocity (Vs), Golsing pulsation index (PI) and pourcelate resistivity index (RI) were registered, together with the instant spectrography of examined artery. Quantitative retinal nerve fiber layer (RNFL) measurements were obtained by scanning laser polarimetry GDx (software version 1.0.14). RNFL was measured automatically in each of 256x 256 pixels and results were compared to the age-, sex- and race-norms. Approximately 150 wide field of view was used. Average thickness, Superior Maximum, Inferior Maximum, maximum modulation and GDx Number were analysed. All results were compared to age norms. Student's t test was used for statistical analysis. RESULTS: In patients with POAG a statistically significant decrease of Vs in ophthalmic artery was detected in 27% of eyes, in central retinal artery in 51% of eyes and in short posterior ciliary arteries in 45% of eyes. In patients with NTG a statistically significant decrease of Vs was detected in ophthalmic artery in 27% of eyes, in central retinal artery in 65% of eyes and in short posterior ciliary arteries in 53% of eyes. RNFL analysis in eyes with POAG showed a decrease in avg. thickness in 80% of analysed eyes, decrease of Superior Maximum in 84% of analysed eyes, decrease of Inferior Maximum in 77.4% of analysed eyes, decrease in maximal modulation in 87% of analysed eyes and increase of GDx Number in 77% of analysed eyes. RNFL analysis in patients with NTG showed a decrease in av. thickness in 73% of analysed eyes, decrease of Superior Maximum in 80.7% of analysed eyes, decrease of Inferior Maximum in 65.7% of analysed eyes, decrease in maximal modulation in 61.5% of analysed eyes and increase of GDx Number in 57.6% of analysed eyes.     

Results of inpatient and outpatient cataract surgery. A historical cohort comparison.

PURPOSE: The transition from inpatient to outpatient cataract surgery during the last decade was not accompanied by prospective investigation of its effect on visual outcomes or surgical complications. The authors performed this study to assess the impact of this transition on surgical results. METHODS: The authors reviewed 600 extracapsular cataract extractions performed by 4 experienced ophthalmic surgeons during a 36-month period; in 300 cases, patients were hospitalized after surgery (inpatient group), and, in 300 cases, patients were never hospitalized (outpatient group). The same surgical techniques were used in all cases. Visual outcome and rates for operative and postoperative complications were compared. RESULTS: There were no statistically significant differences between the inpatient and outpatient groups for visual acuity. Excluding patients with pre-existing nonlenticular ocular disease, a best-corrected visual acuity of 20/40 or better was achieved in 93.1% of inpatient cases and in 97.2% of outpatient cases 6 months after surgery. Postoperative, clinically apparent cystoid macular edema was more common in the inpatient group (P = 0.03); however, after exclusion of patients with diabetes, hypertension, age younger than 65 years, and eyes with pre-existing nonlenticular disease, there was no statistically significant difference between groups. No significant differences in rates for other operative and postoperative complications were identified, including wound dehiscence, unplanned postoperative filtering blebs, infectious endophthalmitis, retinal detachment, persistent iridocyclitis, glaucoma, and corneal edema. CONCLUSION: This study does not demonstrate that the transition to outpatient cataract extractions has had an adverse effect on surgical outcomes.     

Expression of neurturin, glial cell line-derived neurotrophic factor, and their receptor components in light-induced retinal degeneration

PURPOSE: Dysregulation of neurturin (NTN) expression has been linked to photoreceptor apoptosis in a mouse model of inherited retinal degeneration. To investigate the extent to which any such dysregulation depends on the nature of the apoptotic trigger, the expression of NTN, glial cell line-derived neurotrophic factor (GDNF), and their corresponding receptor components were compared in a rat model of light-induced retinal degeneration. METHODS: Retinal expression of NTN, GDNF, their corresponding receptors GFRalpha-2 and -1, the transmembrane receptor tyrosine kinase (Ret), and cSrc-p60, a member of the cytoplasmic protein-tyrosine kinases family, were analyzed by Western blot analysis and immunocytochemistry in cyclic light- and dark-reared rats in the presence and absence of intense light exposure. RESULTS: All components for NTN-mediated signaling activation are present in rat photoreceptors and retinal pigment epithelium, the cells primarily affected by light-induced damage. The expression levels of GDNF, its receptor components, and NTN, were not affected by light-induced stress. However, GFRalpha-2 expression strikingly increased with the extent of retinal damage, especially at the photoreceptors, in contrast to decreased levels that were observed previously in an inherited degeneration model. CONCLUSIONS: The present study indicates that the expression of receptors of the GDNF family is independently regulated in normal and light-damaged rat retina, and in conjunction with previous work, suggests that the pattern of modulation of these genes during photoreceptor degeneration is determined by the nature of the apoptotic trigger. Such differential responses to different modes of retinal degeneration may reflect influences of the neurotrophic system on photoreceptor survival or in the regulation of neuronal plasticity.     

Atypical Retinal Hemorrhages after Vitrectomy for Idiopathic Macular Hole: Possible Toxicity of Brilliant Blue G

PurposeTo describe the development of multiple retinal hemorrhages after uncomplicated macular hole (MH) surgery, and to determine the associated factors.MethodsThe medical records of 163 patients (167 eyes) diagnosed with idiopathic MHs and who underwent surgery at Pusan National University Hospital between March 2016 and July 2018 were retrospectively reviewed. The development of retinal hemorrhages was evaluated using ultra-widefield fundus photographs. Multiple retinal hemorrhages were defined as three or more dot or blot hemorrhages that had not been observed before and during the surgery. The patients were divided into two groups according to the presence of multiple retinal hemorrhages. The variable parameters were compared between the two groups to find the risk factors. The associated factors were evaluated further for the independent factor using multiple logistic regression analysis.ResultsMultiple retinal hemorrhages were observed in 31 eyes (18.6%) after MH surgery. The associated factors were the surgical induction of posterior vitreous detachment (PVD) (p = 0.003), use of the internal limiting membrane flap technique (p = 0.028), and staining with Brilliant Blue G (BBG) (p = 0.003). Retinal hemorrhages were exclusively observed in eyes in which BBG was used. Surgical PVD induction was the only independent risk factor (odds ratio, 13.099; p = 0.013). No statistically significant differences were observed between the two groups in the postoperative visual outcomes and MH closure rate. Additionally, patients who underwent surgery for idiopathic epiretinal membrane during the study period were reviewed to validate the above findings. Multiple retinal hemorrhages were noted in only one case (0.4%) in which BBG was used after surgical induction of PVD.ConclusionsMultiple retinal hemorrhages after MH surgery appear to be related to the intravitreal use of BBG in eyes that sustained mechanical damage because of surgical induction of PVD; however, they did not affect surgical outcomes.     

Management of exudative retinal detachment in choroidal melanoma

Exudative retinal detachment is the most common source of visual loss associated with malignant melanoma of the uveal tract. Management has historically been conservative, leading to irreversible visual loss from photoreceptor damage during the several months needed for post-radiation resolution. The purpose of this paper is to describe timely vitreoretinal surgical intervention for exudative retinal detachments associated with choroidal melanomas. This was an interventional case series including six consecutive patients with malignant melanoma who experienced VA reduction secondary to associated exudative retinal detachment. Patients underwent complete ophthalmic evaluation and B-scan ultrasound. Treatment included proton-beam radiation or brachytherapy, prognostic transretinal tumour biopsy with 25-gauge vitrector and surgical treatment of exudative retinal detachment, including vitrectomy and drainage of subretinal fluid at the time of irradiation. Successful management of exudative retinal detachments associated with choroidal melanomas was observed in all cases, with significant restoration of vision. Steady regression of tumour thickness was noted clinically and ultrasonographically, without extrascleral extension or metastasis, and with no recurrence of exudative retinal detachment found over follow up. In the present study, the investigators have showed effective surgical treatment of exudative retinal detachment associated with malignant melanoma. These patients had significant restoration of vision, confirming that timely intervention of exudative retinal detachment associated with malignant melanoma can reverse visual loss in these patients. These findings are in contrast to previous reports of irreversible visual loss after exudative retinal detachments, and suggest that photoreceptor atrophy might play a role in visual loss associated with chronic exudative retinal detachments.     

Are Ophthalmic Surgeons Aware that Starch Powdered Surgical Gloves are a Risk Factor in Ocular Surgery?

Purpose: To assess the level of awareness among UK ophthalmic surgeons of the potential risks from starch powdered surgical gloves during ophthalmic surgery and to show by electron microscopy that starch granule contamination can occur during ophthalmic surgery. Setting: A sample (N = 46) of UK ophthalmologists from the North of England, UK. Methods: Type of glove usage and awareness of the possible risks from starch powdered surgical gloves were assessed by means of a questionnaire sent to ophthalmic surgeons in the North of England. The surface of a polymethylmethacrylate (PMMA) intraocular lens (IOL) handled with a starch powdered surgical glove was examined by electron microscopy for evidence of starch contamination. Results: Of the sampled ophthalmic surgeons (46), 89.1% considered it important to use starch free surgical gloves and the 84.8% already did so. Starch granule contamination was seen by electron microscopy on the surface of a PMMA IOL which had been handled with starch powdered surgical gloves. Conclusions: Although there has been sporadic attention in the ophthalmic literature to the risks associated with starch powdered surgical gloves in ophthalmology, up to 15% of UK ophthalmic surgeons may still be using starch powdered gloves. The authors show that starch powder contamination of ophthalmic materials can actually occur and remind ophthalmologists that this has been reported in the literature as a possible cause of sterile intra and extraocular inflammation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Adaptive changes in visual cell transduction protein levels: effect of light.

Long-term environmental light-mediated changes in visual cell transduction proteins were studied to assess the influence of rearing environment on their levels and their potential effects on intense light-induced retinal damage. The levels of rhodopsin, S-antigen and the alpha subunit of transducin were measured in whole eye detergent extracts, retinal homogenates or rod outer segments isolated from rats reared in weak cyclic light or darkness, and following a change in rearing environment. Rats changed from weak cyclic light to darkness had 22% more rhodopsin per eye than cyclic-light rats after 12-14 days in the new environment. Western trans-blot analysis of retinal proteins from these dark-maintained animals contained 65% higher levels of immunologically detectable alpha transducin; S-antigen levels were approximately 45% lower than in cyclic-light rats. In rats changed from the dark environment to weak cyclic light, rhodopsin levels decreased by 18% during a comparable period; retinal alpha transducin was 35% lower, S-antigen was 30% higher. At various times after the change in rearing environment, some rats were exposed to intense visible light to determine their susceptibility to retinal damage. Two weeks after an 8-hr exposure, cyclic-light reared rats had rhodopsin levels only 10% lower than control (2.1 nmol per eye). However, rhodopsin was 75% lower when cyclic-light rats were maintained in darkness for 2 weeks before intense light. For animals originally reared in darkness, rhodopsin was 78% lower following 8 hr of intense light, whereas only 30% rhodopsin loss occurred in dark-reared rats after previous maintenance for 2 weeks in weak cyclic-light.(ABSTRACT TRUNCATED AT 250 WORDS)     

Threshold and retreatment parameters of NPe6 photodynamic therapy in retinal and choroidal vessels

BACKGROUND AND OBJECTIVE: To determine the threshold fluence for producing choroidal and retinal vascular occlusion with mono-L-aspartyl chlorin e6 (NPe6) photodynamic therapy (PDT) during primary treatment and the effect of retreatment. METHODS: Primary treatment: Rats, rabbits, and monkeys underwent NPe6 PDT to determine the threshold fluences for choroidal and retinal vessel occlusion. The threshold was determined by analyzing fluorescein angiograms for areas of nonperfusion. Retreatment: Dutch-belted rabbits underwent NPe6 PDT followed by fluorescein angiography. Rabbits were retreated one week later at the same parameters. RESULTS: Fluence levels and vascular damage thresholds were always higher for retinal than for choroidal vascular occlusion. Retreatment caused choroidal vessel closure at all tested fluences but retinal capillaries closed only at a fluence > 17.7 J/cm2. CONCLUSION: NPe6 PDT has a lower threshold to occlude choroidal vessels than retinal vessels. The cumulative effect of retreatment does not damage retinal vessels unless the threshold is exceeded during a single retreatment session.