ObjectiveTo observe the effect of mild anemia on prognosis of hyperplastic diabetic retinopathy (PDR) treated by pars plana vitrectomy (PPV). MethodsA retrospective case-control study. From January 2021 to December 2022, 147 PDR patients with 147 eyes who received PPV treatment at Shenyang He Eye Hospital were included in the study. There were 147 eyes in 147 cases, 82 eyes in 82 males and 65 eyes in 65 females. Age was 25-79 (53.54±12.74) years old. A hemoglobin (Hb) of 90 to 120 g/L in men and 90 to 110 g/L in women was defined as mild anemia. According to Hb results, the patients were divided into mild anemia group and non-anemia group, with 39 cases (39 eyes) and 108 cases (108 eyes), respectively. The best corrected visual acuity (BCVA) test was performed using the international standard logarithmic visual acuity scale before and after the surgery, which was statistically converted to minimum resolved logarithmic (logMAR) visual acuity. The logMAR BCVA of the affected eye was 0.2-2.5 (1.60±0.62) before surgery. According to whether the BCVA improved by more than 3 lines 6 months after surgery, the affected eyes were divided into BCVA improved by more than 3 lines and BCVA improved by less than 3 lines, 117 eyes and 30 eyes, respectively. The patient's body mass index (BMI), BCVA at 6 months after surgery, and the occurrence of neovascular glaucoma (NVG) and recurrence of vitreous hemorrhage (RVH) were recorded. Independent sample t test was used for comparison between groups. Multivariate logistic regression analysis was performed to analyze the influencing factors of increased BCVA ≥3 rows after surgery. ResultsSix months after surgery, the logMAR BCVA of patients in mild anemia group and non-anemia group were 0.97±0.87 and 0.68±0.63, respectively. BCVA increased ≥3 in 26 (66.7%, 26/39) and 91 (84.3%, 91/108) eyes, respectively. logMAR BCVA (t=2.234) and BCVA increased by ≥3 rows of eyes (χ2=5.460) between the two groups, the differences were statistically significant (P=0.027, 0.019). Logistic regression analysis showed that baseline logMAR BCVA [odds ratio (OR) =4.291, 95% confidence interval (CI) 1.918-9.600, P＜0.001)], BMI (OR=1.248, 95%CI 1.057-1.472, P=0.009), the number of retinal laser photocoagulation during surgery (OR=1.001, 95%CI 1.000-1.002, P=0.038), mild anemia (OR=0.360, 95%CI 0.131-0.993, P=0.048), postoperative NVG (OR=0.156, 95%CI 0.033-0.726, P=0.018) and RVH (OR=0.264, 95%CI 0.086-0.808, P=0.020) were independent factors for BCVA improvement ≥3 lines after PPV. ConclusionsMild anemia has a certain effect on BCVA improvement after PPV of PDR. Mild anemia, post-operative NVG and RVH were independent risk factors for increasing BCVA ≥3 lines after PPV in PDR patients.
ObjectiveTo evaluate changes in operational effectiveness after the implementation of ambulatory surgical management in pars plana vitrectomy (PPV). MethodsA retrospective clinical study. 17 528 surgeries in 10 895 eyes of 10 895 patients who underwent minimally invasive PPV on an ambulatory and/or inpatient basis at Tianjin Medical University Eye Hospital from August 2015 to June 2023 were included in this study. Among them, 5 346 eyes in 5 346 cases were male; 5 549 eyes in 5 549 cases were female. The age ranged from 0 to 95 years, with the mean age of (57.74±13.15) years. 6 381 surgeries in 3 615 eyes from August 2015 to December 2018 (the initial period of day surgery) were used as the control group; 11 147 surgeries in 7 280 eyes from January 2019 to June 2023 (the expanded period of day surgery) were used as the observation group. According to the management mode of ambulatory surgery, the observation group was subdivided into the decentralized management group (January 2019 to December 2020) and the centralized management group (January 2021 to June 2023), with 2 905 and 4 375 eyes and 4 646 and 6 501 surgeries, respectively. Changes in the percentage of day surgery, average hospitalization days, and average unplanned reoperation rate were compared. The Mann-Whitney U test was used to compare numerical variables between groups; the chi-square test or Fisher's exact test was used to compare categorical variables. ResultsThe number of cases of daytime PPV performed in the observation group and control group was 7 852 (70.44%, 7 852/11 147) and 24 (0.38%, 24/6 381) cases, respectively, and the average hospitalization days were 1 (1) and 5 (3) d. Compared with the control group, the observation group had a significantly higher percentage of day surgery (χ2=8 051.01) and a considerably lower mean hospitalization day (Z=4 536 844.50), and the differences were statistically significant (P＜0.000 1). The mean hospitalization days in the decentralized and centralized management groups were 2 (3) and 1 (0) d, respectively, and unplanned reoperations were 34 (0.73%, 34/4 646) and 171 (2.63%, 171/6 501) eyes, respectively. Compared with the decentralized management group, average hospitalization days was significantly lower (Z=1 436.94) and unplanned reoperation rate was significantly higher (χ2=54.10) were significantly lower in the centralized management group, both of which were statistically significant (P＜0.000 1). ConclusionPPV ambulatory management model can significantly reduce the average hospitalization day, but also results in higher rates of unplanned reoperations.
Objective To observe the therapeutic effect of autologous neurosensory retinal transplantation in repairing unhealed giant macular hole after pars plana vitrectomy (PPV). MethodsA prospective clinical study. From July 2022 to December 2023, 12 patients (12 eyes) with refractory large macular hole who received autologous neurosensory retinal transplantation treatment in Department of Ophthalmology of the First Affiliated Hospital of Zhengzhou University were selected for the study. The macular hole in affected eyes still did not close after PPV combined with inner limiting membrane removal or tamponade, and the diameter of macular hole were greater than 600 μm. All affected eyes received best corrected visual acuity (BCVA) and optical coherence tomography (OCT) examinations. The BCVA examination employed the international standard visual acuity chart, with results converted to logarithm of the minimum angle of resolution (logMAR) visual acuity for statistical analysis. During the surgery, a piece of healthy retinal neuroepithelial tissue, approximately 0.3 optic disc diameters larger than the macular hole, was removed from the upper retinal periphery and used as a graft. The graft was inserted into the macular hole with the aid of intraoperative OCT. Post-surgery, the vitreous cavity was filled with silicone oil or sterile air. The follow-up period after surgery was 6 months. The thickness of the retinal grafts was measured using the same equipment as before surgery at 3 days, 1, 3, and 6 months post-surgery. The primary focus was on observing the macular hole closure rate and changes in BCVA at 6 months post-operation. A paired t-test was used to compare BCVA before and after surgery. Results In the sample of 12 cases (12 eyes), there were 5 males with 5 eyes and 7 females with 7 eyes. The mean age was (50.4±12.6) years. The mean macular hole diameter was (1 085.6±344.0) μm; The mean eye axis length was (27.64±4.19) mm. At 6 months after surgery, all affected eyes showed macular hole were completely closed (100.0%, 12/12). The thickness of the retinal graft was measured as (206.8±21.0), (170.8±23.3), (165.6±31.6), and (157.9±31.1) μm at 3 days, 1, 3, and 6 months post-surgery, respectively. At before and 6 months after surgery, the logMAR BCVA of the affected eyes was 1.28±0.39 and 0.95±0.22, respectively. The difference in logMAR BCVA before and after surgery was statistically significant (t=3.40, P＜0.05). Conclusion Autologous neurosensory retinal transplantation could effectively improve the closure rate of refractory large macular hole and improve or stabilize vision in the short run.
ObjectiveTo investigate the clinical characteristics of patients with high-myopia macular hole retinal detachment (MHRD) combined with choroidal detachment and to preliminarily analyze factors associated with postoperative hole closure. MethodsA retrospective clinical case series study. A total of 68 patients with high myopia (68 eyes) with MHRD diagnosed by Department of Ophthalmology, Peking University People’s Hospital from January 2019 to April 2024 were included in this study. Among them, there were 14 males (14 eyes) and 54 females (54 eyes). The mean age was (61.10±9.66) years. All eyes were treated with pars plana vitrectomy (PPV) combined with silicone oil or gas filling. Best corrected visual acuity (BCVA), intraocular pressure, and B-mode ultrasonography were performed. The BCVA test was performed using the Snellen visual acuity chart, which was statistically converted to logarithm of the minimum angle of resolution (logMAR) visual acuity. The range of choroidal detachment was defined according to the number of involved quadrants observed in B-mode ultrasound or surgery, which was divided into 1 to 4 quadrants. Axial length (AL) was measured under retinal reattachment. In 68 eyes, there were 17 eyes with choroidal detachment and 51 eyes without choroidal detachment, respectively. There were 17 eyes with choroidal detachment, and the detachment range involved 1, 2, 2 and 12 eyes in 1, 2, 3 and 4 quadrants, respectively. During operation, 13% C3F8 was filled in 2 eyes, all of which were not complicated with choroidal detachment. 66 eyes were filled with silicone oil. According to whether the patients were complicated with choroidal detachment, the patients were divided into the group without choroidal detachment and the group with choroidal detachment. Independent sample t test, Welch two-sample t test or Mann-Whitney U test were used for comparison between groups. Generalized linear regression and logistic regression were used to analyze the relationship between the aperture size of postoperative unclosed holes and the closed hole after surgery and clinical factors. ResultsAt 3 months after surgery, the logMAR BCVA of the affected eye was 1.29±0.43, with a preoperative to postoperative difference ranging from −1.60 to 0.70 (−0.51±0.51) logMAR units. The AL ranged from 26.6 to 34.3 (29.60±2.12) mm. Among 68 eyes, macular hole of 37 (54.4%, 37/68) eyes were open and 31 (45.6%, 31/68) eyes were closed, respectively. The hole diameter of the open eye was (753±424) µm. There was no significant difference in age, course of disease and AL between the two groups (W=412.0, 477.5, 427.0; P＞0.05). Before operation, BCVA in patients with choroidal detachment was worse (W=257.5) and intraocular pressure was lower (t=4.051) in patients with choroidal detachment compared with those without choroidal detachment, with statistical significance (P＜0.05). At 3 months after surgery, BCVA in patients with choroidal detachment was significantly worse than that in patients without choroidal detachment, with statistical significance (W=284.0, P＜0.05). There were no significant differences in logMAR BCVA difference (t=0.616) and macular hole closure rate (χ2=0.000) before and after surgery (P＞0.05). The reoperation rate of retinal detachment due to persistent or recurrent retinal detachment was significantly higher in the group with choroid detachment than in the group without choroid detachment, and the difference was statistically significant (odds ratio=6.424, P＜0.05). Logistic regression analysis showed that young age was significantly correlated with macular hole closure failure after surgery (β=0.077, P=0.015). There was no correlation between AL, duration of disease, BCVA before surgery, intraocular pressure, wether combined with choroid detachment range and postoperative hole closure (β=−0.072, 0.000, 0.672, −0.085, −0.391; P＞0.05). ConclusionsConcomitant choroidal detachment adversely affected on both pre-operative and post-operative visual acuity in high myopia MHRD. It is closely associated with the risk of recurrent retinal detachment and the needs of multiple operations, but has no significant effect on hole closure rate. Lower age of onset may be a risk factor for macular hole closure.
Diabetic retinopathy (DR) has become an important cause of irreversible vision loss worldwide. Intravitreal injection of anti-vascular endothelial growth factor (VEGF) drugs is an important method to the treatment of DR. However, the current anti-VEGF treatment regimen is not uniform. Anti-VEGF injection was preferred and then delayed combined with laser had better prognostic effect. The best time for operation was 5-7 days after injection of anti-VEGF drugs. Pars plana vitrectomy, intraoperative and postoperative on-demand anti-VEGF drugs injection can significantly improve patient prognosis and reduce complications, but further research is needed to strike a balance between the economic burden and the number of injections. Various anti-VEGF drugs have their own advantages for different diseases and should be selected according to the characteristics of the diseases and drugs. Anti-VEGF drugs combined with antioxidants may further improve DR outcomes. Future studies should pay more attention to the optimization and personalization of anti-VEGF drugs application programs to meet the therapeutic needs of different patients.
ObjectiveTo systematically review the efficacy of preoperative corticosteroids use as an adjunctive treatment for rhegmatogenous retinal detachment associated with choroidal detachment (RRDCD). MethodsA evidence-based medicine study. The National Library of Medicine's PubMed, Web of Science, CNKI, and WanFang database were searched. Clinical controlled studies were selected the study object was RRDCD patients and the interventions were preoperative corticosteroids used as an adjunctive treatment. The search was conducted from January 2000 to January 2022. Duplicated, incomplete, or irrelevant articles were excluded. The conventional meta-analysis was used to evaluate the efficacy of corticosteroids used before surgery. The network meta-analysis was used to directly or indirectly compare the efficacy of oral corticosteroids or intravenous dexamethasone, peribulbar injection of glucocorticoids, prednisolone acetate eye-drops, intravitreal injection of triamcinolone acetonide (TA) and posterior sub-tenon injection of triamcinolone acetonide. Publication bias was evaluated by funnel plot. ResultsAccording to the search strategy, 43 articles were initially retrieved, and 929 eyes of 13 articles were finally included for analysis; 6 and 10 articles were included in the traditional meta-analysis and the network meta-analysis. Among the 6 studies included in the conventional meta-analysis, 5 studies were retrospective and 1 study was a randomized controlled trial, involving a total of 575 eyes. The analysis results showed that there was no significant difference in the primary retinal reattachment rate between the corticosteroids group and the control group [odds ratio (OR)= 1.53, 95% confidence interval (CI) 0.67-3.53, P=0.314]. Among the 10 studies included in the network meta-analysis, 7 studies were retrospective trials, 2 studies were randomized controlled trials, and 1 study was prospective trial, involving a total of 575 eyes. The analysis results showed that there were significant differences in the primary retinal reattachment rate between the triamcinolone acetonide intravitreal injection group and the no corticosteroid treatment group (OR=4.09, 95%CI 1.06-15.79). Sub-tenon injection triamcinolone acetonide had a higher incidence rate of ocular hypertension than oral glucocorticoid or intravenous dexamethasone (OR= 4.47, 95%CI 1.42-14.13). ConclusionsTriamcinolone acetonide intravitreal injection before surgery can improve the primary retinal reattachment rate in RRDCD patients. Patients with the posterior sub-tenon injection of triamcinolone acetonide should be alert to elevated intraocular pressure.
Objective To observe the clinical efficacy of pars plana vitrectomy (PPV) combined with dexamethasone intravitreal implant (DEX) in the treatment of proliferative diabetic retinopathy (PDR). MethodsA prospective randomized controlled study. A total of 57 PDR patients with 79 eyes diagnosed by Department of Ophthalmology of The First Affiliated Hospital of Nanjing Medical University from May 2021 to February 2023 were included in the study. Best corrected visual acuity (BCVA) and optical coherence tomography (OCT) were performed in all affected eyes. Central macular thickness (CMT) was measured by OCT. The patients were randomly divided into control group and experimental group, with 27 cases and 35 eyes and 30 cases and 44 eyes, respectively. All eyes were treated with routine 25G PPV and intraoperative whole-retina laser photocoagulation. At the end of the operation, the experimental group was given 0.7 mg DEX intravitreal injection. At 1, 4, 12, and 24 weeks after operation, the same equipment and methods were used for relevant examinations. The improvement after surgery was assessed according to the diabetic retinopathy severity score (DRSS). Mixed analysis of variance was used to compare logarithm of the minimum angle of resolution BCVA and CMT between the two groups and within the two groups before and after operation. ResultsAt 1, 4, 12 and 24 weeks after surgery, BCVA was significantly improved at different time points after surgery, and the differences were statistically significant (P＜0.001). At different time after operation, BCVA and CMT in experimental groups were significantly better than that in control group, with statistical significance (P＜0.05). Compared with the CMT before surgery, the CMT at all time point after surgery in experimental group were significantly decreased, and the difference were statistically significant (P＜0.05). There was no significant difference one week after eye operation in control group (P=0.315). At 4, 12 and 24 weeks after operation, CMT decreased in control group, and the differences were statistically significant (P＜0.05). Compared with before surgery, DRSS increased two steps higher at 1, 4, 12 and 24 weeks after surgery in 20 (45.45%, 20/44), 26 (59.10%, 26/44), 32 (72.73%, 32/44) and 31 (70.45%, 31/44) eyes in the experimental groups, respectively. The control group consisted of 15 (42.86%, 15/35), 15 (42.86%, 15/35), 16 (45.71%, 16/35) and 18 (51.43%, 18/35) eyes, respectively. There was no significant difference in DRSS at 1, 4 and 24 weeks after operation between the control group and the experimental group (P=0.817, 0.178, 0.105). At 12 weeks after surgery, the difference was statistically significant (P=0.020). ConclusionPPV combined with intravitreal injection of DEX in the treatment of PDR can improve postoperative visual acuity, alleviate postoperative macular edema and improve the severity of DR.
Pars plana vitrectomy (PPV) combined with intraocular tamponade surgery is one of the main surgical methods for treating retinal detachment. Due to the use of filling substances, patients need to maintain specific postures after the operation to promote retinal reattachment and reduce the occurrence of complications. Currently, during the process of performing postural management for such surgical patients, there are problems such as low compliance and insufficient monitoring and management. Clinical medical staff have actively explored ways to improve the quality of positioning management, but no corresponding norms and consensus have been formed. The standards implemented by different places are closely related to the degree of medical experience. The evaluation of the performance of the patient's position by the medical care mainly relies on the patient's self-report or the nurse's inspection record, which lacks continuity and accuracy. In the future, it is necessary to further promote the development and transformation of auxiliary tools, implement scientific monitoring and management of patients with the help of artificial intelligence, formulate individualized plans and dynamically adjust them according to the patient's condition, and ensure the effect and improve patient satisfaction.
ObjectiveTo compare the efficacy of pars plana vitrectomy (PPV) combined with subretinal or intravitreal injection of Conbercept for the treatment of refractory diabetic macular edema (DME). MethodsA retrospective case control study. From June 2022 to March 2024, 32 eyes of 32 patients with refractory DME diagnosed at The Affiliated Eye Hospital of Nanchang University were included in the study. There were 17 male cases with 17 eyes and 15 female cases with 15 eyes. Age was (57.44±8.99) years old; The duration of diabetes was (12.72±6.11) years. All patients had received regular treatment with anti-vascular endothelial growth factor (VEGF) drugs or corticosteroid drugs for at least 5 times, and had undergone focal retinal laser photocoagulation or panretinal laser photocoagulation, the central macular thickness (CMT) persisted or decreased by less than 50 μm. All affected eyes underwent best-corrected visual acuity (BCVA), intraocular pressure, optical coherence tomography (OCT), microperimetry, and laboratory glycated hemoglobin (HbA1c) testing. BCVA was measured using a standard logarithmic visual acuity chart, and converted to the logarithm of the minimum angle of resolution (logMAR) for statistical analysis. CMT was measured using an OCT device. Microperimetry was performed using an MP-3 microperimeter, recording the mean sensitivity (MS) of the retina within a 12° range of the fovea. The affected eyes were treated with 23G PPV combined with internal limiting membrane peeling and either macular subretinal or intravitreal injection of Conbercept, and were divided into subretinal injection group and the intravitreal injection group, each consisting of 16 cases and 16 eyes. The same equipment and methods as before surgery were used for related examinations at 1, 3, and 6 months post-surgery. Changes in BCVA, CMT, and MS were observed and compared, as well as the number of additional anti-VEGF treatments required within 6 months after surgery. Intergroup comparisons were made using independent samples t tests, and repeated measures data were analyzed using repeated measures analysis of variance. ResultsThe age (t=－0.271), gender composition (χ2=0.001), duration of diabetes (Z=－0.868), HbA1c (t=－0.789), intraocular pressure (t=1.689), logMAR BCVA (t=1.393), CMT (t=－0.613), MS (Z=－0.132), and the number of anti-VEGF injections (t=－0.752) between the subretinal injection group and the intravitreal injection group showed no statistically significant differences (P＞0.05). The within-subject effects comparison of BCVA, CMT, and MS at 1, 3, and 6 months post-surgery compared to pre-surgery for all affected eyes showed statistically significant differences (F=8.060, 125.722, 39.054; P＜0.05). The overall comparison of logMAR BCVA between the subretinal and intravitreal injection groups post-surgery showed no statistically significant difference (F=0.662, P=0.422), however, comparisons of CMT (F=4.540) and MS (F=6.066) showed statistically significant differences (P＜0.05). At 1, 3, and 6 months post-surgery, comparisons of logMAR BCVA between the two groups showed no statistically significant differences (t=－0.123, 0.239, 1.087; P＞0.05), comparisons of CMT showed statistically significant differences (t=－3.474, －4.832, －2.482; P＜0.05), comparisons of MS showed statistically significant differences at 1 and 3 months (t=－2.940, －2.545; P＜0.05), but not at 6 months (t=－1.527, P＞0.05). At 6 months post-surgery, the number of additional intravitreal anti-VEGF injections required in the subretinal and intravitreal injection groups showed a statistically significant difference (Z=－2.033, P=0.042). During the follow-up period and at the final follow-up, no complications such as injection site bleeding, retinal detachment, vitreous hemorrhage, macular hole, or retinal pigment epithelial tear or atrophy occurred in all affected eyes. ConclusionCompared with intravitreal injection, subretinal injection of Conbercept for the treatment of refractory DME has more advantages in reducing macular edema and improving visual function in the macular area, and also reduces the number of postoperative anti-VEGF drug treatments.
Objective To compare and observe the efficacy and safety of pars plana vitrectomy (PPV) combined with 41G ultrafine needle injection of balanced salt solution (BSS) and internal limiting membrane inversion and coverage in the treatment of large-diameter macular hole (MH). MethodsA prospective study. From April 2023 to April 2024, 42 patients (42 eyes) diagnosed with large-diameter MH at The Affiliated Eye Hospital of Nanchang University were included in the study. The substrate diameters (BD) of MH are all greater than 1 000 μm. All affected eyes underwent best corrected visual acuity (BCVA), microvisual field, optical coherence tomography (OCT), and OCT angiography (OCTA) examinations before surgery. BCVA examination was conducted using the international standard logarithmic visual acuity chart, and the statistics were converted to the logarithm of the minimum angle of resolution (logMAR) visual acuity. Microfield-of-view examination records the mean retinal sensitivity (MS) within a 12° range of the fovea. The minimum diameter (MD) and BD of the hole were measured by OCT and the MH index (MHI) was calculated. OCTA measures the area and perimeter (PERIM) of the foveal avascular zone (FAZ) in the fovea centralis, as well as the retinal vessel length density (VLD) and vessel perfusion density (VPD) in the central area. The affected eyes were divided into the observation group (22 eyes, treated with PPV combined with 41G ultra-micro needle subretinal injection of BSS and the control group (20 eyes, treated with PPV combined with internal limiting membrane inversion and coverage) according to the random number table method. The patients were followed up for 6 months after the operation, and the above indicators were reexamined at 1, 3 and 6 months. The changes of BCVA, MS, FAZ parameters, VLD, VPD before and after the operation, as well as the closure of the hole and the occurrence of complications were compared between the two groups. The independent sample t test was used for comparison between groups. The correlation between postoperative indicators and preoperative structural parameters was analyzed using Pearson analysis. ResultsIn the 22 eyes of the observation group, the hole closure rate was 100.0% (22/22) 6 months after the operation, and the complete closure rate was 90.9% (20/22). In the control group of 20 eyes, the closure rate was 95.0% (19/20), and the complete closure rate was 90.0% (18/20). The hole closure rate of the affected eyes in the observation group was better than that in the control group, but the difference was not statistically significant (χ2=1.736, P=0.420). logMAR BCVA, MS, FAZ area, PERIM, VLD and VPD at each time point after the operation in both groups were significantly improved compared with those before the operation, and the differences were statistically significant (P＜0.05). The results of Pearson correlation analysis showed that in the observation group, logMAR BCVA at 6 months after surgery was positively correlated with BD before surgery (r=0.340, P=0.029), and negatively correlated with MHI before surgery (r=−0.350, P=0.023). Six months after the operation, MS was positively correlated with the preoperative hole height and MHI (r=0.330, P=0.034). In the control group, 6 months after the operation, MS was negatively correlated with BD before the operation (r=−0.480, P=0.032), and positively correlated with MHI before the operation (r=0.510, P=0.027). Six months after the operation, the FAZ area of the affected eyes in the observation group [(0.17±0.09) mm2] was larger than that in the control group [(0.12±0.07) mm2], and the difference was statistically significant (t=−0.340, P=0.025). No complications such as abnormal intraocular pressure, retinal pigment epithelium injury or retinal detachment occurred in all the affected eyes after the surgery. ConclusionsPPV combined with 41G ultra-micro needle subretinal injection of BSS for the treatment of large-diameter MH has a high rate of hole closure and good safety. Larger BD and MD, lower MHI and hole height before surgery may affect the recovery of visual function after surgery.