PseudoSegRT: efficient pseudo-labelling for intraoperative OCT segmentation.

PURPOSE: Robotic ophthalmic microsurgery has significant potential to help improve the success of challenging procedures and overcome the physical limitations of the surgeon. Intraoperative optical coherence tomography (iOCT) has been reported for the visualisation of ophthalmic surgical manoeuvres, where deep learning methods can be used for real-time tissue segmentation and surgical tool tracking. However, many of these methods rely heavily on labelled datasets, where producing annotated segmentation datasets is a time-consuming and tedious task. METHODS: To address this challenge, we propose a robust and efficient semi-supervised method for boundary segmentation in retinal OCT to guide a robotic surgical system. The proposed method uses U-Net as the base model and implements a pseudo-labelling strategy which combines the labelled data with unlabelled OCT scans during training. After training, the model is optimised and accelerated with the use of TensorRT. RESULTS: Compared with fully supervised learning, the pseudo-labelling method can improve the generalisability of the model and show better performance for unseen data from a different distribution using only 2% of labelled training samples. The accelerated GPU inference takes less than 1 millisecond per frame with FP16 precision. CONCLUSION: Our approach demonstrates the potential of using pseudo-labelling strategies in real-time OCT segmentation tasks to guide robotic systems. Furthermore, the accelerated GPU inference of our network is highly promising for segmenting OCT images and guiding the position of a surgical tool (e.g. needle) for sub-retinal injections.

Posterior vitreal detachment in decompression illness--case report and discussion.

We report a case of a healthy leisure diver presenting with simultaneous unilateral posterior vitreous detachment and decompression illness. The literature is reviewed for both conditions. There are no known publications associating these 2 entities and leads us to propose that nitrogen bubble formation could have contributed to the etiology of vitreal separation from the retina.

A prospective study of binocular visual function before and after successful surgery to remove a unilateral epiretinal membrane.

OBJECTIVE: To examine the effect of a unilateral epiretinal membrane (uERM) on visual acuity, stereopsis, and motor fusion in patients before and after successful surgery to remove the membrane. DESIGN: Cohort study. PARTICIPANTS: Twenty-seven consecutive patients undergoing surgery to remove an idiopathic uERM and 30 normal control subjects. METHODS: Patients underwent full orthoptic examination before and between 3 and 6 months after surgery to remove a uERM. Stereoacuities were analyzed statistically using the Wilcoxon signed-rank test, Mann-Whitney U test, and Spearman correlation. Motor fusion ranges and visual acuities were compared using paired and unpaired t tests, with correlations examined by linear regression. MAIN OUTCOME MEASURES: Snellen visual acuity, TNO (stereoscopic acuity test of the Netherlands; Netherlands Organisation for Applied Scientific Research; Laméris Ootech BV, Nieuwegein, the Netherlands) and Titmus stereoacuity, motor fusion range. RESULTS: Postoperative acuity and improvement in visual acuity after removal of a uERM were better in patients with a shorter duration of symptoms. Stereoacuity was substantially reduced in the presence of a uERM (TNO, P<0.001; Titmus, P<0.001; Mann-Whitney U test), as were total motor fusion ranges at near and distance (near P = 0.002; distance P = 0.015; t test). Stereoacuity was worse in patients with symptoms of longer duration (TNO, P = 0.21; Titmus, P = 0.045; Spearman rank correlation). After successful surgery, stereoscopic function improved. This improvement occurred mainly in those patients with better preoperative stereoacuity and a shorter duration of symptoms. CONCLUSIONS: Improvement in visual acuity after surgery was greater in patients with visual symptoms of shorter duration. A uERM adversely affected stereoscopic function, an effect that increased with time. The best monocular and binocular visual outcomes occurred in those patients who had earlier surgery.

Immunopathology of intraocular silicone oil: enucleated eyes.

AIMS: To characterise the distribution of silicone oil in ocular tissues in globes enucleated after complicated retinal detachment, and to document the distribution and nature of any associated inflammatory response. METHOD: 9 enucleated globes that had previously undergone retinal detachment surgery with silicone oil and 7 control globes that had undergone enucleation after retinal detachment surgery (n = 2) or ocular trauma (n = 5) were studied. Sections were histologically examined using light microscopy to document the distribution of silicone oil in ocular tissues. Immunohistochemical analysis was carried out using the ABC technique and a panel of monoclonal and polyclonal antibodies. Electron microscopy was undertaken to observe the penetration of silicone oil in the trabecular meshwork of the anterior chamber drainage angle. RESULTS: Silicone oil was distributed throughout the globes-notably in the iris, ciliary body, retina, trabecular meshwork and epiretinal membranes. Focal areas of intraretinal silicone were associated with disorganised retinal architecture, retinectomy sites or subretinal oil. The distribution of macrophages was closely related to the distribution of silicone oil. T and B lymphocytes were not associated with silicone oil unless additional pathology was also present-for example, cyclitic membrane or uveitis. One of the nine eyes had silicone oil present in the optic nerve. In the control globes, the inflammatory response was mediated primarily by macrophages and T lymphocytes, and was less marked than that observed in the silicone oil globes. CONCLUSION: This study shows that silicone oil may be sequestered in varied ocular tissues and is associated with localised inflammation mediated by macrophages.

Immunopathology of intraocular silicone oil: retina and epiretinal membranes.

AIMS: To determine the inflammatory response in retina and epiretinal membranes after intraocular silicone oil tamponade. METHODS: 14 proliferative vitreoretinopathy (PVR) epiretinal membranes, 33 retro-oil epiretinal membranes, 19 retinectomies, 14 retro-oil retinectomies and 37 idiopathic epiretinal membranes (controls) underwent immunohistochemical analysis using the avidin-biotin complex technique and a panel of monoclonal and polyclonal antibodies. The number of positive cells counted in five 0.5 mm diameter fields of immunohistochemical sections was graded on a score of 1-4. RESULTS: Macrophage cell counts were significantly greater in membranes with a history of exposure to silicone oil (p<0.001). An inflammatory response could be observed within 1 month of silicone oil exchange, and the intensity seemed to be unrelated to the duration of exposure. Macrophages were confined to epiretinal membranes on the surface of retinectomy specimens in 10 of 14 cases and intraretinal macrophages were observed only in specimens with gliotic retina. T and B lymphocytes were rarely seen in the specimens examined. Marked glial cell up regulation was observed in 11 of 16 retinectomy specimens and in 8 of 11 retro-oil retinectomies. Glial cell content was variable in the membranes, but there was a trend of increased presence after exposure to silicone oil. CONCLUSION: This study has shown that the use of silicone oil is accompanied by an inflammatory reaction, primarily mediated by bloodborne macrophages. This response can be observed within 1 month of silicone oil injection and continues after silicone oil removal. Retinal surgeons should be aware of the potential secondary effects of intraocular silicone oil when they are considering its use (and removal) in vitreoretinal surgery.

Proliferative vitreoretinopathy: developments in pathogenesis and treatment.

Proliferative vitreoretinopathy is an abnormal wound-healing response following retinal detachment and occurs in 5% to 10% of cases. It is now possible to treat this once-blinding condition. However, proliferative vitreoretinopathy still remains the most common cause of failure to reattach the retina. Recent work has helped to unravel the causes of proliferative vitreoretinopathy, and new adjuvant treatments are being evaluated to improve the success rate of retinal reattachment surgery, both anatomically and functionally. At present, preventative treatment has only been found to work in high-risk cases. It is hoped that improvement in targeted immunosupression will eventually reduce the incidence of proliferative vitreoretinopathy. At the current time, the management of proliferative vitreoretinopathy still remains a surgical skill.

A randomized controlled trial of combined 5-fluorouracil and low-molecular-weight heparin in management of established proliferative vitreoretinopathy.

OBJECTIVE: To determine the efficacy of a combination of 5-fluorouracil and low-molecular-weight heparin (LMWH) to improve the outcome of surgery for established proliferative vitreoretinopathy (PVR). DESIGN: Double-masked, prospective, randomized, placebo-controlled clinical trial. SETTING: Three tertiary-referral teaching hospital vitreoretinal surgical units. PATIENTS: One hundred fifty-seven patients with established PVR (grade C, anterior or posterior) undergoing vitrectomy surgery. INTERVENTION: All patients underwent vitreoretinal surgery and silicone oil exchange with or without membrane peeling and/or retinectomy. Patients were randomly allocated to perioperative infusion with or without 5-fluorouracil (200 microg/ml) and LMWH (5 IU/ml) in Hartmann's solution for 1 hour. OUTCOME MEASURES: The primary outcome measure was defined as posterior retinal reattachment after removal of silicone oil without any reoperations at 6 months. Secondary outcome measures recorded were posterior retinal reattachment, localized/tractional retinal detachment, visual acuity, macular pucker, hypotony, glaucoma, keratopathy, and cataract. Removal of silicone oil and reoperations were also recorded. RESULTS: Overall, at 6 months 84% of patients had full retinal reattachment and 94% had stable posterior retinal reattachment. There was no significant difference in success in the primary outcome measure (56%, treatment group; 51%, placebo group; P = 0.59) or in secondary outcome measures or rates of complications. Secondary macular pucker occurred less often in the treatment group (6% vs. 17% at 6 months, P = 0.068). CONCLUSIONS: A perioperative infusion of combined 5-fluorouracil and LMWH does not significantly increase the success rate of vitreoretinal surgery for established PVR.

Resources involved in managing retinal detachment complicated by proliferative vitreoretinopathy.

PURPOSE: To report the differences in cost of treatment and outcome in retinal detachment (RD) cases with and without proliferative vitreoretinopathy (PVR). METHODS: Analysis of clinical trial databases of RD observed in 190 eyes of 190 patients. Eyes were classified as no PVR, developing PVR, or established PVR. For each eye, total cost of treatment undertaken on Moorfields Eye Hospital vitreoretinal unit, final retinal status, and best-corrected visual acuity were recorded. RESULTS: Management of patients who developed PVR involved approximately double the resources of RD without PVR. Eyes with pre-exiting PVR had similar resource input to those with RD without PVR. Patients who developed PVR had a mean of 3.7 operations (including subsequent cataract surgery) compared to 1.8 and 2.1 respectively for noncomplicated RD and pre-existing PVR. Anatomic success and visual outcome was significantly worse in eyes with PVR. CONCLUSIONS: Treatment of eyes that developed PVR after initial surgery cost significantly more than eyes with no PVR or established PVR (P < 0.01). Improvements in the management of RD aimed at preventing PVR and advances in PVR treatment may have significant financial as well as clinical benefits.

Visual perception during phacoemulsification cataract surgery under topical and regional anaesthesia.

PURPOSE: To compare the subjective visual experiences of patients during phacoemulsification and intraocular lens (IOL) implantation using regional and topical anaesthesia. DESIGN: A prospective, cohort, questionnaire-based study. METHODS: The study cohort consisted of 247 patients without pre-existing ocular pathology who underwent routine phacoemulsification and IOL implantation. The mean age of the subjects was 75.4 +/- 9.4 years and 34.5% of them had a history of cataract surgery. Three different methods of local anaesthesia were used: 66 (26.7%) of the patients were given topical anaesthesia (TA); 74 (30.0%) were given sub-Tenon's anaesthesia (SA), and 107(43.3%) were given peribulbar anaesthesia (PA). The patients were interviewed immediately after surgery by theatre staff using a standardized questionnaire that investigated their intraoperative visual experiences. RESULTS: There was no significant difference between the three methods of anaesthesia regarding light perception during the surgery. However, patients undergoing surgery under TA experienced brighter light intensity levels (78.3%) than those given SA (50.0%) and PA (55.7%) (p = 0.02). A total of 69.6% of subjects who received TA reported visual perception of colours during surgery, as opposed to 56.8% of SA recipients and 49.0% of PA recipients (p = 0.02). In addition, patients under TA were more aware of surgical instruments (26.1%) than those under SA (10.8%) and PA (15.9%) (p = 0.08). The vast majority of patients in all three groups found the visual experience to be non-frightening. There were no associations between intraoperative visual impression and age or sex. Although not statistically significant (p = 0.06), prior cataract surgery appeared to alleviate some of the anxiety associated with the visual experience. CONCLUSION: Patients undergoing regional and topical anaesthesia experience a wide variety of visual sensations during surgery. The differences in visual impressions between the groups may reflect the varying degrees of optic nerve blockade that result from the different anaesthetics.

Same-day versus first-day review of intraocular pressure after uneventful phacoemulsification.

PURPOSE: To compare the incidence and the spectrum of postoperative complications detected when the intraocular pressure (IOP) is reviewed 4 to 6 hours or the day after uneventful phacoemulsification cataract extraction and intraocular lens (IOL) implantation. SETTING: Royal Free Hospital, London, United Kingdom. METHODS: The study cohort consisted of 141 patients who had uneventful phacoemulsification and IOL implantation under regional (peribulbar/topical) or general anesthesia. Postoperative evaluation of the patients was performed by an ophthalmologist using a standard form at 4 to 6 hours or 24 hours. RESULTS: The mean IOP at 4 to 6 hours and 24 hours was 22.85 mm Hg +/- 9.56 (SD) and 19.44 +/- 7.04 mm Hg, respectively. The IOP was more likely to be greater than 30 mm Hg when measured on the same day, resulting in a significantly higher intervention rate than on the first day (P =.037). The best corrected visual acuity was significantly better at 24 hours than at the same-day review (P <.001). There was no significant difference in the extent of anterior chamber activity, patient comfort, or state of the wound between the same- or next-day follow-up. All patients attended a follow-up appointment 3 weeks after surgery, had an IOP of 21 mm Hg or less, and were subsequently discharged. CONCLUSIONS: The results indicate that moderate IOP spikes (<40 mm Hg) can be left untreated if they are not associated with corneal edema or patient discomfort as they decline spontaneously. Before they are discharged, patients with compromised optic discs or predisposed to retinal or optic nerve pathology should be carefully evaluated the day after surgery to treat IOP elevations.