Surgically induced astigmatism after 23-gauge transconjunctival sutureless vitrectomy

Intraoperative choroidal detachment during small-gauge vitrectomy: analysis of causes, anatomic, and visual outcomes

INTRODUCTION

To investigate the incidence and causes of intraoperative choroidal detachment (CD) during small-gauge vitrectomy, as well as the anatomic and visual outcomes.

METHODS

We retrospectively reviewed the medical records of 1026 consecutive patients who underwent small-gauge vitrectomy from June 2017 to December 2018 at Zhongshan Ophthalmic Centre, Guangzhou, China. Data on the presence, location, and extent of intraoperative CD and its relationship to the infusion cannula were collected. Patient demographic characteristics and postoperative anatomic and visual outcomes were also assessed.

RESULTS

A total of six cases were found to have intraoperative CD, including two with serous CD, three with limited haemorrhagic CD, and one with CD caused by inadvertent perfusion of gas during air/fluid exchange. Retraction of the infusion cannula and acute ocular hypotony were found to be the main causes of intraoperative CD in five out of the six cases. The best-corrected visual acuity of all cases significantly improved after the surgery.

CONCLUSION

The incidence of intraoperative CD during small-gauge vitrectomy is low; the predominant causes are retraction of the infusion cannula and acute ocular hypotony. Immediate awareness and timely closure of the incision may contribute to a better surgical prognosis.

Long-term Analysis of Surgically Induced Astigmatism after Combined Vitrectomy and Cataract Surgery versus Cataract Surgery Alone

Purpose: To compare the long-term changes in surgically induced astigmatism (SIA) in patients who underwent 23-gauge sutureless vitrectomy and cataract surgery together with patients who underwent cataract surgery only.Methods: We retrospectively reviewed SIA changes for 1 year after surgery in patients who received only cataract surgery using phacoemulsification (group 1) and patients who underwent 23-gauge sutureless vitrectomy and cataract surgery together (group 2). Flat keratometry (K1), steep keratometry (K2), and astigmatism axis were measured with automatic keratometry before and after the surgery. Vector analysis was used to calculate SIA at 1, 3, 6, and 12 months postoperatively. We then examined whether the SIA values at each time point were different between the two groups.Results: A total of 86 eyes were included in this study (group 1, n = 45; group 2, n = 41). The mean SIA values calculated at 1, 3, 6, and 12 months after surgery in group 1 were 0.83 ± 0.37, 0.69 ± 0.39, 0.60 ± 0.33, and 0.59 ± 0.33, respectively. In group 2, the values were 0.82 ± 0.47, 0.69 ± 0.38, 0.62 ± 0.28, and 0.61 ± 0.30, respectively. Over time, SIA decreased in both groups (all p < 0.001). There was no significant difference in the mean SIA between the two groups at each follow-up time point after surgery (p = 0.296, p = 0.728, p = 0.361, and p = 0.356, respectively).Conclusions: When 23-gauge sutureless vitrectomy and cataract surgery were performed together, the astigmatism change caused by surgery did not show a significant difference compared with that of the group who received cataract surgery only. Thus, 23-gauge sutureless vitrectomy may not significantly affect corneal astigmatism.

Design Parameters for a Small-Gauge Fragmatome

Purpose

Manufacturers of surgical instrumentation have increasingly sought to decrease the size of ophthalmic surgical instruments. We have used finite element modeling to model the stress and strain present in a fragmatome as a function of driving frequency and fragmatome dimensions.

Methods

Finite element calculations using the COMSOL Multiphysics system v3.5 were used to elucidate the influence of wall thickness, length, and excitation frequency on a titanium fragmatome tube with outer diameters of 20, 23, 25, and 27 gauge.

Results

By coupling structural mechanics, fluid mechanics, and acoustical physics, we were able to determine the eigenfrequencies (resonant frequencies) as well as parameters in which the von Mises stress in a fragmatome tube exceeds the yield strength, leading to destruction of the instrument.

Conclusion

Solid fragmatomes have far fewer possible failure modes than fragmatomes with a standard wall thickness. Eigenfrequency analysis and finite element calculations can be critical in predicting potentially catastrophic designs in modern surgical instruments.

Translational Relevance

Instruments developed for microsurgical applications cannot always simply be scaled down versions of conventional instruments. Such an approach can lead to potentially dangerous intraoperative failures, such as a fragmatome shattering inside the eye. Modern engineering techniques are increasingly necessary to investigate potential instrument failure mechanisms and to optimize device performance in a design in silico before in vivo testing.

Evaluation of corneal topographic changes and surgically induced astigmatism after transconjunctival 27-gauge microincision vitrectomy surgery

PURPOSE

To evaluate the corneal topographic changes and postvitrectomy astigmatism after 27-gauge (g) microincision vitrectomy surgery (MIVS) by using Pentacam HR-Scheimpflug imaging system.

METHODS

This prospective descriptive study included 30 eyes of 30 patients who underwent 27-g MIVS. All eyes underwent a Pentacam HR examination preoperatively and on the first week, first month and third month postoperatively. The power of the corneal astigmatism, mean keratometry (K m), K 1 and K 2 values and corneal asphericity (Q value) values for the both front and back surfaces of the cornea, index of surface variance (ISV), index of vertical asymmetry (IVA), index of height asymmetry (IHA), index of height decentration (IHD) and higher-order aberrations including coma, trefoil, spherical aberration, higher-order root-mean-square and total RMS were recorded. Additionally, the mean induced astigmatism was estimated by vector analysis.

RESULTS

No statistically significant changes were observed in the mean power of corneal astigmatism, mean keratometry, K 1 and K 2 values, corneal asphericity values, ISV, IVA, IHA, IHD and higher-order aberrations on the first week, first month and third month after the operation. The mean surgically induced astigmatism was calculated as 0.23 ± 0.11 D on the first week, 0.19 ± 0.10 D on the first month and 0.19 ± 0.08 D on the third month postoperatively.

CONCLUSION

Minor corneal surface and induced astigmatic changes are expected to result in rapid visual rehabilitation after pars plana vitrectomy with the 27-g MIVS system.

Surgically Induced Corneal Astigmatism Following Intravitreal Ranibizumab Injection

Purpose :

To evaluate surgically induced astigmatism (SIA) after an intravitreal ranibizumab (IVR) injection.

Methods :

Fifty eight eyes of 58 patients who underwent IVR injection due to age-related macular degeneration (wet form) or macular edema were included in this study. Patients’ pre- and postoperative detailed ophthalmologic examinations were done and topographic keratometric values (K1, K2) were noted. Pre- and postoperative measurements were compared.

Results :

The mean preoperative astigmatism of 0.87 Diopters (D) was found to be 0.95 D, 0.75 D, 0.82 D and 0.78 D on the 1st day, 3rd day, 1st week and 1st month, respectively. After injection, absolute change in astigmatism was found to be 0.08 D, 0.12 D, 0.05 D and 0.09 D on the 1st day, 3rd day, 1st week and 1st month, respectively. The absolute change in astigmatism seemed to be insignificant in terms of refractive analysis, however; when we performed a vectorial analysis, which takes into account changes in the axis of astigmatism, the mean value of induced astigmatism were found to be 0.33±0.22 D, 0.32±0.29 D, 0.41±0.37 D, 0.46±0.32 D on the 1st day, 3rd day, 1st week and on 1st month, respectively.

Conclusion :

Intravitreal injection is a minimally invasive ophthalmologic procedure, however; it may still cause statistically significant induced astigmatism when evaluated from a vectorial point of view.

Surgical induced astigmatism correlated with corneal pachymetry and intraocular pressure: transconjunctival sutureless 23-gauge versus 20-gauge sutured vitrectomy in diabetes mellitus

AIM

To determine the difference of surgical induced astigmatism between conventional 20-gauge sutured vitrectomy and 23-gauge transconjunctival sutureless vitrectomy, and the influence of corneal pachymetry and intraocular pressure (IOP) on surgical induced astigmatism in diabetic patients.

METHODS

This retrospective, consecutive case series consisted of 40 eyes of 38 diabetic subjects who underwent either 20-gauge or 23-gauge vitrectomy. The corneal curvature and thickness were measured with Scheimpflug imaging before surgery and 1wk; 1, 3mo after surgery. We compared the surgical induced astigmatism (SIA) on the true net power in 23-gauge group with that in 20-gauge group. We determined the correlation between corneal thickness change ratio, IOP and SIA measured by Pentacam.

RESULTS

The mean SIAs were 1.082±0.085 D (mean±SEM), 0.689±0.070 D and 0.459±0.063 D at postoperative 1wk; 1, 3mo respectively in diabetic subjects. The vitrectomy induced astigmatisms were declined significantly with time (F 2,36=33.629, P=0.000) postoperatively. The 23-gauge surgery group induced significantly less astigmatism than 20-gauge surgery group (F -1,37=11.046, P=0.020). Corneal thickness in diabetes elevated after surgery (F 3,78=10.532, P=0.000). The linear regression analysis at postoperatively 1wk went as: SIA=-4.519+4.931 change ratio (Port3) +0.026 IOP (R(2)=0.46, P=0.000), whereas the rate of corneal thickness change and IOP showed no correlation with the change of astigmatism at postoperatively 1 and 3mo.

CONCLUSION

There are significant serial changes in both 20-gauge and 23-gauge group in diabetic subjects. 23-gauge induce less astigmatism than 20-gauge and become stable more rapidly than 20-gauge. The elevation of corneal thickness and IOP was associated with increased astigmatim at the early postoperative stage both in 23-gauge and 20-gauge surgery group.

Comparison of surgically-induced astigmatism after combined phacoemulsification and 23-gauge vitrectomy: 2.2-mm vs. 2.75-mm cataract surgery

Purpose

The 2.2-mm microincision cataract surgery and small-gauge vitrectomy system is known to result in less surgically-induced astigmatism (SIA) in comparison to conventional surgical methods. We compared the amounts of SIA after combined phacoemulsification and 23-gauge transconjunctival sutureless vitrectomy (23G-TSV) using the 2.2-mm microincision and 2.75-mm standard incision methods.

Methods

We studied 59 patients (61 eyes) who underwent combined phacoemulsification and 23G-TSV from November 2008 to September 2012. Twenty-eight patients (28 eyes) underwent 2.2-mm microincision coaxial phacoemulsification, and 31 patients (33 eyes) underwent 2.75-mm standard incision phacoemulsification. SIA was evaluated using Naeser's polar method with the simulated keratometric values obtained from corneal topography. Preoperative and 1-week and 1-month postoperative KP (Naeser's polar value along the specific axis) and ΔKP values were compared between the 2.2-mm microincision and 2.75-mm standard incision groups.

Results

One week after surgery, both groups exhibited similar amounts of SIA (-ΔKP[120], 0.40 ± 0.41 vs. 0.51 ± 0.56 diopters [D]; p = 0.390). One month after surgery, however, the amount of SIA was significantly smaller in the 2.2-mm microincision group as compared to the 2.75-mm standard incision group (-ΔKP[120], 0.31 ± 0.54 vs. 0.56 ± 0.42 D; p = 0.045).

Conclusions

In combined phacoemulsification with 23G-TSV, 2.2-mm microincision coaxial phacoemulsification induces less SIA than does 2.75-mm standard coaxial phacoemulsification.

Comparison of two scleral incision techniques in 23-gauge transconjunctival vitrectomy

BACKGROUND AND OBJECTIVE

To compare two 23-gauge transconjunctival vitrectomy incision techniques, parallel and perpendicular to the alignment of scleral fibers, in terms of hypotony and postoperative intraocular pressure (IOP).

PATIENTS AND METHODS

Fifty-three eyes of 53 patients who underwent 23-gauge one-step trocar pars plana vitrectomy were randomly assigned to undergo scleral incision parallel (group 1, 26 eyes) or perpendicular (group 2, 27 eyes) to the limbus. Patients were observed postoperatively for wound healing, leakage, endophthalmitis, IOP, and hypotony at 1 day, 1 week, and 1, 3, 6, and 9 months.

RESULTS

No difference in preoperative IOP was observed (P = .229). Postoperative IOP was significantly lower in group 2 (P = .009). Hypotony rates did not differ between the groups. Intraocular gas or silicone tamponade was used intraoperatively in 26 cases. In cases in which no gas or silicone was given (n = 27), IOP measurements were significantly lower in group 2 (P = .021). There was no difference in hypotony ratios for gas/silicone injection versus no injection (P = 1.00) or in postoperative visual acuity (P = .350). Visual acuity improved significantly in both groups at follow-up examinations.

CONCLUSION

Parallel and perpendicular incisions resulted in similar postoperative hypotony rates, but perpendicular incisions were associated with lower IOP.

Postoperative vitreous hemorrhage after diabetic 23-gauge pars plana vitrectomy

PURPOSE

To report the frequency of postoperative vitreous hemorrhage (VH) in eyes that underwent primary 23-gauge pars plana vitrectomy (PPV) for nonclearing VH resulting from proliferative diabetic retinopathy, as well as associated risk factors.

DESIGN

Retrospective, consecutive, interventional case series.

METHODS

SETTING

Institutional (Retina Service of Wills Eye Institute).

STUDY POPULATION

One hundred seventy-three eyes of 157 patients.

INTERVENTION

Twenty-three-gauge PPV for nonclearing diabetic VH.

MAIN OUTCOME MEASURES

Percentage of eyes in which postoperative VH developed, categorized as early, delayed, or severe persistent, as well as percentage requiring reoperation.

RESULTS

During a mean follow-up of 32 weeks, 56 (32%) of 173 eyes demonstrated postoperative VH, categorized as early (8 eyes; 5%), delayed (13 eyes; 8%), or severe persistent (35 eyes; 20%). Twenty-two (13%) of 173 eyes required reoperation: 4 (50%) of 8 in the early group, 8 (62%) of 13 in the delayed group, and 10 (29%) of 35 in the severe persistent group. Mean preoperative logarithm of the minimum angle of resolution visual acuity was 1.5 (Snellen equivalent, approximately 20/600); mean postoperative VA was 0.65 (Snellen equivalent, approximately 20/90), a gain of 0.85 (P < .0001). Thirty-four (27%) of 127 eyes with complete scatter photocoagulation before undergoing PPV compared with 22 (48%) of 46 eyes with incomplete scatter photocoagulation before undergoing PPV demonstrated postoperative VH (P = .002). Other factors associated with postoperative VH included younger age (P = .022) and phakia (P = .036).

CONCLUSIONS

Postoperative VH was not uncommon after initial 23-gauge PPV for diabetic VH and was associated with incomplete scatter photocoagulation, younger age, and phakia before PPV. However, only a minority of patients required reoperation.

Combined 23-gauge sutureless vitrectomy and clear corneal phacoemulsification in patients with proliferative diabetic retinopathy

PURPOSE

To evaluate the results and complications of combined 23-gauge sutureless vitrectomy, clear corneal phacoemulsification, and intraocular lens implantation in patients with proliferative diabetic retinopathy.

METHODS

This was a retrospective, consecutive, noncomparative, interventional case series of 136 eyes of 108 patients who underwent combined sutureless vitrectomy and clear corneal cataract surgery for the complications of proliferative diabetic retinopathy. The main outcome measures were visual outcomes and surgical complications.

RESULTS

Main indications for the combined surgery were vitreous hemorrhage (78 eyes, 57.4%) and tractional retinal detachment (36 eyes, 28.7%). The logarithm of the minimum angle of resolution visual acuity (mean ± SD) improved from 0.86 ± 0.59 preoperatively to 0.39 ± 0.52 six months postoperatively (P < 0.0001). Intraoperative retinal tear occurred in 7 eyes (5.1%) and postoperative vitreous hemorrhage in 10 eyes (7.5%). Even in the absence of suturing of sclerotomy sites, only 1 eye (0.7%) had postoperative hypotony (<6 mmHg). During the 6 months after surgery, only 1 eye (0.7%) developed neovascular glaucoma and 6 eyes (4.4%) required a repeat vitrectomy (3 for retinal detachment and 3 for vitreous hemorrhage).

CONCLUSION

Combined 23-gauge sutureless vitrectomy and clear corneal phacoemulsification in patients with proliferative diabetic retinopathy was safe and effective. It may have not only the known advantages of conventional combined surgery but also additionally those such as faster visual rehabilitation and less conjunctival fibrosis.

Comparative study of 23-gauge vitrectomy versus 20-gauge vitrectomy for the treatment of rhegmatogenous retinal detachment

PURPOSE

To compare the safety and efficacy of 20- and 23-gauge pars plana vitrectomy (PPV) for the management of primary rhegmatogenous retinal detachment (RD) with proliferative vitreoretinopathy (PVR) grade B or less.

METHODS

This comparative nested case-control study included 35 consecutive 23-gauge transconjunctival PPV cases matched (1:1) with 35 cases of 20-gauge PPV (from a prospective cohort of 1,150 patients) for the baseline visual acuity (VA), axial length, lens and macular status, the location and number of breaks, and PVR grade. All patients had complete PPV, cryotherapy, fluid-gas exchange, and a minimum follow-up of 6 months. The exclusion criteria were eyes with previous vitreoretinal surgery, combined vitrectomy and cataract surgery, RD secondary to trauma or macular hole, diabetic retinopathy, aphakic eyes, giant tears, or posteriorly located breaks precluding treatment using transconjunctival cryotherapy.

RESULTS

Baseline examination disclosed pseudophakia in 77.1%, high myopia in 11.4%, 2.7 ± 2.2 retinal breaks/eye, attached macula in 37.1%, and PVR grade B in 24.3% of the cases. The mean operative time and intraoperative complication rate (11.4%) were similar in both groups. In the 23-G group, we noted three cases of iatrogenic retinal tears and one case of choroidal detachment secondary to a dislodgment of the infusion line. Suturing the sclerotomy sites or the conjunctiva was required in 5.7 and 51% of the eyes, respectively. The single reattachment rate was similar in both groups, 74.3% in the 20-G group, and 80% in the 23-G group. The final anatomical success rate was 97% in the two groups. Mean preoperative VA of 1.2 ± 0.9 logMAR improved similarly in both groups to 0.4 ± 0.4 at the 6-month visit. A final vision of 20/40 or better was achieved similarly in 62.9% of the eyes in the 20-G group and 60% in the 23-G group.

CONCLUSIONS

Twenty-three-gauge PPV provides anatomical and visual results similar to the 20-G technique for the management of uncomplicated rhegmatogenous RD.

Advantages and limitations of small gauge vitrectomy

Small gauge vitrectomy utilizing 23- and 25-gauge instrumentation has definite advantages, but also limitations, due to the physics of smaller instruments and sutureless surgery. Higher infusion and aspiration pressures are needed to remove the vitreous using 23- and 25-gauge probes. The advantages include decreased surgical times, less tissue manipulation, reduced inflammation and pain postoperatively with more rapid visual recovery. A disadvantage is greater instrument flexion than 20-gauge probes, making small gauge vitrectomy more appropriate for indications such as vitreous opacities, epiretinal membranes, macular holes, and simple retinal detachments. There are also some increased complications related to small gauge vitrectomy, including dislocation of cannulas intraoperatively, early postoperative hypotony, choroidal detachment, and possibly an increased risk of infectious endophthalmitis.