Analysis of Posterior Corneal Surgically Induced Astigmatism Following Cataract Surgery With a 1.8-mm Temporal Clear Corneal Incision

PURPOSE

To determine posterior corneal surgically induced astigmatism (SIA) when using a temporal clear corneal incision and the IOLMaster 700 (Carl Zeiss Meditec AG) for biometric measurements and to determine whether posterior corneal SIA can be predicted from preoperative data.

METHODS

A total of 258 consecutive eyes of 258 patients underwent cataract surgery with a 1.8-mm temporal clear corneal incision. Biometry measurements were taken preoperatively and 6 weeks postoperatively using the IOLMaster 700. Using vector analysis, the SIA of the posterior cornea was calculated.

RESULTS

The centroid of posterior corneal SIA was 0.01 diopters (D) @159 ± 0.14 D. The mean posterior corneal SIA was 0.12 D ± 0.07 D. Posterior corneal SIA magnitude was 0.25 D or less in 95% of patients. There was no correlation found between posterior corneal SIA magnitude and any preoperative measurement.

CONCLUSIONS

The authors suggest not adjusting for posterior corneal SIA if using a small caliber, temporal incision. It was not possible to predict posterior corneal SIA from preoperative biometric measurements. [J Refract Surg. 2023;39(6):381-386.].

Leftover Astigmatism: The Missing Link Between Measured and Calculated Posterior Corneal Astigmatism

PURPOSE

To quantify the total eye astigmatism that is not accounted for by measurement of anterior corneal astigmatism and posterior corneal astigmatism and knowledge of intraocular lens (IOL) astigmatism and assess whether it is correlated with candidate sources of or correlates with leftover astigmatism.

METHODS

Vector subtraction of anterior corneal, posterior corneal, and IOL astigmatism from total eye astigmatism as represented by spectacle astigmatism to yield a value of "leftover" astigmatism that is neither corneal nor lenticular. This value was derived in a series of eyes following cataract surgery. This novel entity was examined for correlation with candidate sources of or correlates with leftover astigmatism.

RESULTS

In 103 pseudophakic eyes with known IOL toricity, mean leftover astigmatism was 0.71 ± 0.43 diopters. This was significantly correlated with against-the-rule anterior corneal astigmatism (P < .001).

CONCLUSIONS

Leftover astigmatism is clinically substantial. Because it is included in IOL cylinder power calculations based on refractive outcome, it may explain why methods of IOL cylinder power calculation using refractive outcome-based adjustments to anterior corneal astigmatism (previously described as adjustments for "posterior corneal astigmatism") are more successful than adjustment on the basis of measured posterior corneal astigmatism. [J Refract Surg. 2022;38(9):559-564.].

Accuracy of the Goggin Nomogram for 0.50 D Steps in Toric IOL Cylinder Power Calculation

PURPOSE

To examine the accuracy of the cylinder power choice for toric intraocular lenses (IOLs) using the Goggin Nomogram, which adjusts anterior keratometric astigmatic power values for the likely effect of posterior corneal and non-corneal, non-lenticular astigmatism.

METHODS

A consecutive, retrospective case series was based at the Queen Elizabeth Hospital and Ashford Advanced Eye Care in Adelaide, Australia. A total of 586 consecutive eyes of 586 patients underwent phacoemulsification surgery with implantation of a Zeiss AT TORBI 709MP or AT LISA Tri Toric 939 MP toric IOL, calculated using the Goggin Nomogram. The median absolute magnitude of error and geometric mean astigmatic correction index in consecutive eyes with toric IOL cylinder powers of 1.00 to 3.00 diopters (D) were analyzed.

RESULTS

Overall, all eyes receiving IOL cylinder powers of 1.00 to 3.00 D inclusive had a median magnitude of error value of 0.19 D (IQR: 0.31) and astigmatic correction index value of 1.03 (IQR: 0.33). For eyes with with-the-rule, against-the-rule, and oblique astigmatism, the median magnitude of error was 0.18 D (interquartile range [IQR]: 0.29), 0.19 D (IQR: 0.31), and 0.17 D (IQR: 0.39), respectively, and the astigmatic correction index was 1.06 (IQR: 0.28), 1.01 (IQR: 0.35) and 1.08 (IQR: 0.32), respectively.

CONCLUSIONS

Goggin Nomogram adjusted keratometry provided optimal refractive astigmatic outcome in IOL cylinder powers of 1.00 to 3.00 D in eyes with with-the-rule, against-the-rule, and oblique astigmatism. Goggin Nomogram adjusted keratometry compensates for both posterior corneal astigmatism and any other source of ocular astigmatism. [J Refract Surg. 2022;38(5):298-303.].

Peripheral Hypertrophic Subepithelial Corneal Degeneration on a Laser-Assisted In Situ Keratomileusis Flap

ABSTRACT

We describe the first reported case of a patient developing peripheral hypertrophic subepithelial corneal degeneration (PHSCD) in the setting of previous femtosecond laser in situ keratomileusis (LASIK). Superficial keratectomy was performed successfully with the complete restoration of the visual acuity, no LASIK flap complications, and no recurrence of PHSCD at 1-year follow-up. Our case indicates that superficial keratectomy can be a safe and effective treatment for PHSCD in the setting of LASIK and raises awareness of the possibility of PHSCD developing in eyes that have undergone prior LASIK.

Evidence-based vitamin supplements for age-related macular degeneration: an analysis of available products

CLINICAL RELEVANCE

A wide range of supplements are available for age-related macular degeneration (AMD); however, clinicians may not be aware of which supplements contain an evidence-based formula.

BACKGROUND

Vitamin and antioxidant supplementation has been shown to be effective in slowing the progression of AMD. The Age-Related Eye Disease Studies (AREDS) group reported an evidence-based formula in the AREDS 2 trials. Commercially available products carry varying degrees of resemblance to this formula.

METHODS

A review of commercially available supplements in pharmacies and websites across Australasia, the United States, the United Kingdom, and Canada was undertaken. Supplements containing all the ingredients of the AREDS 2 recipe were included. The dose, formulation, and cost of the supplements were reviewed.

RESULTS

Sixty-six products were reviewed. Forty-three products contained all the AREDS 2 ingredients and were therefore included for analysis. Twenty products contained all ingredients at 100% or more of the recommended dose, and 23 products contained some ingredients at a lower dose. The cost of the products varied from Australian dollar (AUD) $0.12 to AUD $6.72 per day. Seven (35%) products were available online only and 13 (65%) products were available both online and in pharmacies. Eight products were available in the United States pharmacies, five products were available in Canadian pharmacies, three products were available in the United Kingdom pharmacies, and one product was available in Australasian pharmacies.

CONCLUSIONS

Commercially available AMD supplements vary widely in price and resemblance to the AREDS 2 formulation. Clinician awareness of this information is important when counselling patients on which supplement is most suitable. The categorisation of products in Table 1 may assist with patient counselling of vitamin supplementation for AMD.

Assessing the Likely Effect of Posterior Corneal Curvature on Toric IOL Calculation for IOLs of 2.50 D or Greater Cylinder Power

PURPOSE

To establish whether average refractive overcorrection or undercorrection of corneal astigmatism based on the orientation (rule) of the astigmatism occurs if toric intraocular lenses (IOLs) are calculated on the basis of anterior corneal measurements in eyes requiring toric IOL cylinder power of 2.50 diopters (D) or greater.

METHODS

One hundred thirteen consecutive eyes with anterior corneal keratometric astigmatism requiring IOL cylinder power of 2.50 D or greater underwent phacoemulsification with IOL powers calculated using anterior corneal curvature data alone. Eyes were grouped as either "with-the-rule" (WTR) or "against-the-rule" (ATR) on the basis of the steep anterior corneal meridian. Targeted and achieved astigmatic outcomes were compared. The main outcome measure was the postoperative refractive astigmatic prediction error.

RESULTS

A mean overcorrection occurred in anterior WTR eyes of 0.16 ± 0.57 D and a mean undercorrection of ATR eyes of -0.14 ± 0.53 D. These were significantly different from the ideal value of zero (WTR: P = .04, ATR: P = .05). Although statistically significant, the effect sizes of these prediction errors were 0.40 for WTR and 0.36 for ATR and the error values fell below a clinically significant value of 0.25 D.

CONCLUSIONS

In eyes requiring toric IOLs of cylinder power 2.50 D or greater, an overcorrection occurs in anterior WTR eyes and an undercorrection in ATR eyes. This probable posterior corneal astigmatism effect is not clinically significant. IOL cylinder powers are sufficiently accurately calculated using unadjusted anterior keratometry values in these eyes. [J Refract Surg. 2017;33(11):730-734.].

Antibiotic prophylaxis in cataract surgery in the setting of penicillin allergy: A decision-making algorithm

Cataract surgery is the most commonly performed surgical procedure in many developed countries. Postoperative endophthalmitis is a rare complication with potentially devastating visual outcomes. Currently, there is no global consensus regarding antibiotic prophylaxis in cataract surgery despite growing evidence of the benefits of prophylactic intracameral cefuroxime at the conclusion of surgery. The decision about which antibiotic regimen to use is further complicated in patients reporting penicillin allergy. Historic statistics suggesting crossreactivity of penicillins and cephalosporins have persisted into modern surgery. It is important for ophthalmologists to consider all available antibiotic options and have an up-to-date knowledge of antibiotic crossreactivity when faced with the dilemma of choosing appropriate antibiotic prophylaxis for patients undergoing cataract surgery with a history of penicillin allergy. Each option carries risks, and the choice may have medicolegal implications in the event of an adverse outcome. We assess the options for antibiotic prophylaxis in cataract surgery in the setting of penicillin allergy and provide an algorithm to assist decision-making for individual patients.

High rate of incidental glaucoma detection in New Zealand

AIM

To investigate how glaucoma is initially detected in New Zealanders and what factors aroused disease suspicion.

METHODS

A postal survey of 500 randomly selected members of the Glaucoma New Zealand database was undertaken in 2012 to analyse factors relating to their initial presentation and diagnosis of glaucoma. Online surveys and telephone interviews were used to increase the response rate.

RESULTS

The overall response rate was 80% (376/468) of eligible participants. The sample had an average age of 76 years. Prior to diagnosis, 80% (290/361) of participants who responded to this question reported no suspicion of glaucoma. A positive family history for glaucoma was the most common reason (71%) for presenting to a health care professional with a suspicion of glaucoma (13% of total sample). After diagnosis, 95% (357/376) of respondents reported that they had informed family members of their diagnosis.

CONCLUSIONS

This study confirmed that the majority of glaucoma was discovered through incidental findings. A positive family history was the most common risk factor prompting examination, knowledge about which appeared to increase dramatically post-diagnosis. These findings indicated that there was potential to educate the public about glaucoma in order to raise awareness and diagnose the disease earlier.