Postoperative Corneal and Surgically Induced Astigmatism following Superior Approach Manual Small Incision Cataract Surgery in Patients with Preoperative Against-the-Rule Astigmatism

Association between the site of clear corneal Phakic intraocular lens implantation incisions and the inflow of ocular surface fluid into the anterior chamber

Background

Posterior chamber phakic intraocular implantable collamer lens (ICL) implantation is an effective surgical option for the management of myopia. Over the past few years, the number of ICL surgeries has significantly increased. Postoperative inflammation and endophthalmitis are among the most serious complications after successful ICL surgery. Sometimes, when the blepharospasm is removed at the end of surgery, a small amount of the ocular surface fluid will flow into the anterior chamber, which can lead to an increased risk of infection and inflammation. However, little attention has been paid to this phenomenon.

Purpose

We conducted a retrospective study to compare the incidence of extraocular fluid inflow into the eye through the clear corneal incision (CCI) at two different positions (superior and temporal sides).

Methods

A total of 116 patients with myopia underwent superior CCI ICL implantation (n = 58) or temporal CCI ICL implantation (n = 58) at our hospital from October to December 2021. The incidence of conjunctival sac fluid entering the anterior chamber after eyelid fixative was removed was compared in both groups.

Results

Both groups were well matched in all parameters. Ocular surface fluid inflow into the anterior chamber was significantly higher in the superior CCI group (25/58, 47.1%) than in the temporal CCI group (1/58, 1.7%) (p < 0.05).

Conclusion

In the patients with ICL implantation, the temporal CCI was better than the superior CCI in avoiding the ocular surface fluid inflow into the anterior chamber, and the potential risk of infection and inflammation was lower.

Twelve month outcome of manual small-incision cataract surgery in Assiut, Egypt: A retrospective study with a large sample size

BACKGROUND

To assess the visual outcome of manual small-incision cataract surgery (MSICS) as well as safety, cost, and time of the procedure.

PATIENTS AND METHODS

A retrospective study involving candidates for cataract surgery with baseline-corrected distance visual acuity (CDVA) ≤20/120. Visual acuity (VA) was the primary outcome measure while surgical complications, cost, and time of surgery were the secondary outcome measures. Follow-up visits were scheduled at 1 day, 1 week, 1 month, and at 6 and 12 months following surgery.

RESULTS

The study enrolled 3007 patients with a mean age of 66.45 ± 17.3 years. Out of 3007 patients, 2774 (92.2%) were legally blind before surgery (CDVA <20/200) which was significantly reduced to 55 patients (1.9%) by 1 month following surgery. Uncorrected distance visual acuity was 20/60 or better in 2098 eyes (69.8%) at 1 month, in 2035 eyes (67.7%) at 6 months, and in 2017 eyes (67.1%) at 12 months. The posterior capsular rupture was the most common intraoperative complication. Corneal edema was the most common immediate postoperative complication while the development of posterior capsular opacification was the leading cause for later impaired VA. The mean cost was approximately equivalent to 20 US dollars. The median duration of surgery was 10 min.

CONCLUSION

MSICS is a safe, cost-effective, and time-saving technique for improving the vision of cataract patients in areas with high cataract surgery volume and limited facilities.

Correction of pre-existing astigmatism by on-axis incision size modulation in manual small-incision cataract surgery

Purpose

To study the effect of wound size modulation on pre-existing astigmatism by on-axis placement of incision in manual small-incision cataract surgery (MSICS).

Methods

In this prospective interventional study conducted at a tertiary care centre, 40 eyes of 40 consecutive senile cataract patients with 1.00-3.00 D corneal astigmatism were enrolled for the study. MSICS by modified Blumenthal's technique was performed through 6.0, 6.5, and 7.0 mm on-axis incision in 1.0-1.49 D (group A), 1.50-1.99 D (group B), and 2.00-3.00 D (group C) astigmatism, respectively. Surgically induced astigmatism (SIA) was calculated by vector analysis and double angle plots (DAP) at 12 weeks postoperatively.

Results

There were 22 males and 18 females with mean age of 58.12 ± 1.18 years. The mean SIA at 12 weeks was 0.85 ± 0.28 D in group A (17 eyes), 1.32 ± 0.65 D in group B (10 eyes), and 1.91 ± 0.69 D in group C (13 eyes). The overall median uncorrected visual acuity was 0.18 (IQR = 0 to 0.2). The mean astigmatism decreased from 1.95 ± 0.74 D to 1.04 + 0.57 D (P = 0.00) in superior incision and from 1.70 + 0.50 D to 0.92 ± 0.45 D (P = 0.00) in temporal incision group with central shift of centroid in all cases.

Conclusion

The customization of on-axis external incision size can be used to manage pre-existing corneal astigmatism of less than 3.00 D using both temporal and superior incisions effectively.

Postoperative astigmatic considerations in manual small-incision cataract surgery - A review

Cataract remains a major cause of visual impairment worldwide including in India. The sutureless manual small-incision cataract surgery (MSICS) as an alternative to phacoemulsification, gives equivalent visual results at lower expenses. Still the procedure is often discredited for higher astigmatism due to the larger size of the incision. High astigmatism is an important cause of poor uncorrected visual acuity after cataract surgery. However, there are enough studies in the literature to prove that surgically induced astigmatism (SIA) can be minimized and also eliminated by adopting appropriate wound construction techniques during surgery. Even pre-existing astigmatism if any can be neutralized by changing wound architecture during surgery. Here, we review the various techniques of scleral tunnel construction described in the literature to care for postoperative astigmatism in MSICS.

Evolution of manual small-incision cataract surgery from 8 mm to 2 mm - A comprehensive review

Cataract is the most common cause of reversible blindness worldwide, accounting for approximately 50% of blindness worldwide. Cataract surgery is the most common surgical procedure performed in routine ophthalmic practice. It has undergone tremendous evolution, and the incision size has progressively reduced from 10-12 mm in extracapsular cataract surgery (ECCE) to 6-8 mm for manual small-incision cataract surgery (MSICS) and 2.2-2.8 mm in phacoemulsification. In a developing country like India, with a massive backlog of cataract, everyone cannot afford private surgery like phacoemulsification. Moreover, annual maintenance of the machine, cost of foldable IOLs, need for greater skill, learning curve, and difficulty in performing the surgery in mature and brown cataracts are other barriers. Due to these factors, MSICS is the surgery of choice in the developing world, with profound societal and economic benefits and similar visual recovery compared to phacoemulsification. During the last two decades, MSICS gained popularity in developing countries and has undergone tremendous advances. This article aims to review the various techniques of MSICS and how the surgery has evolved over the years, particularly focusing on the current technique of 2-mm MSICS.

Precision and refractive predictability of a new nomogram for femtosecond laser-assisted corneal arcuate incisions

PURPOSE

Validating a new nomogram for low to moderate astigmatism (0.75 D to 2.5 D) correction with epithelium- and Bowman-penetrating femtosecond laser-assisted arcuate incisions.

METHODOLOGY

Prospective, interventional case series at the Augen- und Laserklinik, Castrop-Rauxel, Germany. Cataract patients with low to moderate corneal astigmatism were treated with femtosecond laser-assisted arcuate incisions. Patients with previous refractive corneal treatment were excluded. Outcome assessment was based on manifest refraction, astigmatic vector analysis and visual acuity.

RESULTS

The study analysed 43 eyes of 33 patients after three months and 35 eyes of 27 patients after 12 months. After 12 months, 100% of all eyes treated had ≤1.0 D and 97% ≤0.5 D of subjective residual astigmatism. Mean residual astigmatism was 0.27 D. 90% of all eyes were within one line of difference between UDVA and CDVA. SEQ Mean Absolute Error was 0.26 D and SEQ. Mean error was -0.08 ± 0.32 D. CI was 0.98 ± 0.2 D, and Index of Success, 0.20 ± 0.18 D.

CONCLUSION

The Castrop nomogram showed results that are comparable to or better than results presented in the literature for existing nomograms. Our results for astigmatic reduction are comparable to published results for TIOL implantation. It seems to be a predictable and safe measure to reduce manifest astigmatism.

Correlation between visual acuity at discharge and on final follow-up in patients undergoing manual small incision cataract surgery

Purpose

The aim of this study was to determine the correlation between visual acuity on discharge and at final follow-up in patients undergoing manual small incision cataract surgery (MSICS) through outreach services of a tertiary care training center.

Methods

A prospective observational study was done to determine the correlation between visual acuity on postoperative day 1 and final follow-up (4-8 weeks) among various categories of surgeons and surgical complications in patients who underwent MSICS between January 2018 and March 2018. Proportions of patients benefitting from refractive correction were also analyzed.

Results

Of the 924 patients who underwent MSICS through outreach services during the study period 841 were eligible for the study. Follow-up rate at 4-8 weeks was 91%. Mean age was 61.6 (SD 9.2) years, 63% were females and 55% were operated by trainees. There was a positive correlation between visual acuity at day one and final follow-up with a Spearman's correlation coefficient of 0.375 and 0.403 for uncorrected (UCVA) and best corrected visual acuity (BCVA) respectively (P < 0.001). The correlation coefficient, while still positive, was lower for trainees (0.287), as compared to consultants (0.492). At least two lines of improvement in visual acuity on refractive correction were found in 77% of patients.

Conclusion

Visual acuity on the day of discharge may be a useful quality indicator of visual outcome for monitoring cataract surgical programs. However, a follow-up at 4-8 weeks is recommended for individual patient benefit and monitoring surgical quality especially in training hospitals.

The effect of glaucoma treatment using high-intensity focused ultrasound on total and corneal astigmatism: a prospective multicentre study

PURPOSE

Ultrasound cycloplasty (UCP) acts through the selective coagulation of the ciliary body using high-intensity focused ultrasound (HIFU) technology. The aim of this study was to investigate whether the application of ultrasound beams targeting the ciliary body using an external probe influences astigmatism.

METHODS

Multicentre, prospective, single-arm, open-label study in adult patients with primary open-angle glaucoma and moderately uncontrolled intraocular pressure (IOP) under glaucoma medication. The primary outcome was induced corneal astigmatism, calculated from topography, and assessed statistically through vector analysis. Secondary outcomes included induced total astigmatism and mean changes from baseline in best-corrected visual acuity (logMAR) and IOP. Subgroup analysis was performed to assess the impact of device centring on corneal and total induced astigmatism.

RESULTS

Fifty eyes were enrolled. Mean age was 69.6 ± 11.3 years. At 1, 3 and 6 months postprocedure, HIFU-induced corneal astigmatism was 0.88 D × 93°, 0.87 D × 106° and 1.16 D × 97°, respectively, while induced total astigmatism was 0.62 D × 103°, 0.42 × 106° and 0.39 × 107°. By the last follow-up, the percentage of patients with <0.50, <1.00, <1.50 and <2.00 D of induced corneal versus total astigmatism was 8.3% versus 46%, 29% versus 66%, 62.5% versus 88% and 79% versus 94%. Visual acuity was statistically significantly impaired at 1 month, but no difference remained by 3 and 6 months postprocedure.

CONCLUSION

Ultrasound cycloplasty procedure is associated with increased corneal astigmatism. However, its impact on total refractive astigmatism is less pronounced.

Characterization of posterior corneal astigmatism in a population with keratoconus

Background: The curvature of the anterior corneal surface is traditionally used as a surrogate to estimate corneal astigmatism. In recent years, increasing importance has been attributed to posterior corneal astigmatism as an indicator. Our aim is to characterize the posterior corneal surface in a population with keratoconus and investigate its predictive value to keratoconus progression. Methods: Retrospective study from a tertiary care centre (Hospital de Santa Maria, Lisbon, Portugal). Eighty-five patients (85 eyes) with keratoconus were included. All patients had two tomographical examinations ≥12 months apart (Pentacam HR). Vector analysis was used to calculate anterior (ACA), posterior (PCA), and total corneal astigmatism (TCA). Multivariate logistic regression was used to assess the predictive value of PCA to keratoconus progression, adjusting for ACA, TCA and several tomographical indices. Results: Study participants had a mean age of 32 (SD = 12.5) years. Mean tomographical keratoconus classification was 2.16 (SD = 0.95), with a mean Kmax of 55.8D (SD = 7.8). Mean power of PCA, ACA and TCA was, respectively, -0.88D (SD = 0.84), 3.74D (SD = 2.36), and 3.06D (SD = 2.01) and its centroids were 0.44D x 15º, 1.65D x 112º, and 1.61D x 106º, respectively. The power of PCA was ≥0.50, 1.00 and 2.00D in 75.3%, 32.9%, and 3.5% of patients, respectively, inducing against-the-rule astigmatism in 60.0% of patients. On average, ACA overestimated TCA in 0.35D x 151º (p < .01). ACA and TCA were highly correlated but showed a lack of agreement for clinical purposes. A predictive role for PCA was excluded. Conclusions: In this population with keratoconus, PCA contributed substantially to TCA. However, PCA was not a valuable predictor for disease progression.

Comparison of incision size and intraocular lens performance after implantation with three preloaded systems and one manual delivery system

Purpose

To compare corneal incision size and intraocular lens (IOL) performance/behavior following implantation with the following delivery systems: system U (UltraSert^®), system S (Hoya iSert^® 250/251), system T (Tecnis^® iTec), and a manual system (Monarch^® III Delivery System).

Setting

Six study sites (four in Spain and two in France).

Design

Prospective, multicenter, parallel-group, randomized, subject-masked, postmarket clinical study.

Materials and methods

Subjects were enrolled based on predetermined inclusion/exclusion criteria. The effectiveness end points compared corneal incision size and enlargement after IOL implantation (day of surgery) among all delivery systems. Exploratory end points included mean enlargement of corneal incision size, rates of trapped trailing haptic, IOL adherence to the plunger tip, nozzle tip splitting, and mean surgically induced astigmatism (SIA) at postoperative visit.

Results

One hundred and nine subjects participated in the study. The mean corneal incision size following IOL implantation was 2.35±0.019 mm for system U, 2.47±0.016 mm for system T, 2.54±0.019 mm for system S, and 2.49±0.011 mm for the manual system. There were five instances of trapped trailing haptic (all system T group, N=26), one instance of IOL adherence to the plunger tip (system S group, N=26), and six instances of nozzle tip splitting (all system S group, N=26). System U had the least SIA (postoperative Day 1) (SIA Centroid = 0.10 diopters [axis: 83.06°]).

Conclusion

Preloaded delivery system U supported the completion of surgery with the smallest incision size, the least SIA (postoperative Day 1), and no trapped trailing haptics or nozzle tip splitting compared to two other preloaded systems and one manual system.