Belin/Ambrósio Enhanced Ectasia Display in cataract surgery and relation to final visual acuity a acuidade visual final

Objective: To analyze and describe the coefficients found on maximum Ambrósio Relational Thickness- Maximum (ART-Max) and Belin/Ambrósio Enhanced Ectasia Display total deviation (BAD-D) in eyes with normal corneal topography subjected to cataract surgery with premium intraocular lens implantation and correlated these data with final visual acuity. Methods: ART-Max and BAD-D data from 103 eyes of patients subjected to implantation of diffractive bifocal intraocular lens, with normal corneal topography who achieved visual acuity of 20/20


INTRODUCTION
With advancements in cataract surgery, the implantation of premium intraocular lenses (IOLs) (toric, bifocal, trifocal, and extended focus) is becoming more common because it reduces the need for glasses. However, the accurate calculation of IOL power is crucial because residual refractive errors result in unsatisfactory surgical outcomes. (1) Refractive surgery using laser in situ keratomileusis (LASIK) or photorefractive keratomileusis (PRK) may be necessary and is the most common solution in cases involving errors in IOL power calculation and consequent residual refractive errors. However, the development of corneal ectasia postoperatively is one issue, although rare in elderly patients, especially after using LASIK in eyes with suspect corneal topography and tomography. (2) Another available options for this biometric error correction could be IOL piggyback, IOL exchange, and limbal relaxation incision (LRI). Therefore, screening for primary corneal ectasias before cataract surgery is essential for the success of refractive surgeries using LASIK and PRK. (3) Topographic examinations are useful for diagnosing mild (subclinical) and moderate ectasia; however, slight changes in the posterior surface of the cornea are largely detected. (4) The first signs of keratoconus may occur on the posterior corneal surface even before changes on the anterior surface and are detectable by pachymetry and posterior elevation maps. Thus, tomography is fundamental and indispensable for screening patients with ectatic disease before refractive and cataract surgery. Although some authors have been proposing prior signs of ectasia in corneal epithelium, our article focused on the posterior surface.
To improve ectasia screening, some authors proposed changing the measurement of the reference sphere by excluding the central 3.5mm region of the optical zone centered on the thinnest portion of the cornea from the analysis and keeping the 8mm (best-fit sphere) reference. (5) The Ambrósio Relational Thickness (ART) evaluates the relationship of the thinnest portion of the cornea with progression indices and shows the Receiver Operating Characteristic (ROC) curve for an average and maximum ART of 0.987 and 0.983, respectively. The best ART-Maximum (ART-Max) cut-off to differentiate normal from keratoconic eyes is 339. (6) Thus, ART-Max values of <339, 339 to 424, and >424 are considered abnormal, borderline, and normal, respectively.
Five parameters are measured in the Belin/Ambrósio Enhanced Ectasia Display (BAD), and the values represent the standard deviation (SD) of the means found in the general population. BAD total deviation (BAD-D) is the average of these parameters and is obtained by regression analysis using a database of normal and keratoconic corneas. BAD-D scores >1.6 are considered as abnormal and are shown in red, whereas scores <1.6 are rated as normal and displayed in green. (7) Even though tomographic analyses using BAD-D scores improve the diagnosis of ectasia after refractive surgery, the implantation of premium IOLs is contraindicated for patients with suspected corneas because residual refractive errors following cataract surgery may not be corrected with corneal refractive procedures. Still, many patients with abnormal BAD-D but normal corneal topography undergo premium IOL implantation and have good visual outcomes. We considered normal corneal topography when the difference in the curvatures between the eyes is less than 1D, higher curvature is less than 47D, I -S indices are less than 1.4 and there is no suspicion of irregularity image at color map.
This study analyzed BAD-D data in patients with normal corneal topography who underwent cataract surgery and premium IOL implantation and correlated final visual acuity (VA) in patients with better surgical outcomes with ART-Max and BAD-D values.

METHODS
This descriptive retrospective quantitative study analyzed BAD data available in the Pentacam (Oculus, Wetzlar, Germany) and data from posterior corneal elevation maps of patients with normal corneal topography in the Topolyzer (Oculus, Wetzlar, Germany), who underwent cataract surgery with implantation of premium IOLs To detect changes in ART-Max and BAD-D values in eyes with better outcomes, the patients included in the analysis were divided into two groups with VA 20/20 and 20/25, respectively, without refractive correction. For toric lenses, only patients with lenses centered on the programmed axis were included in the study. Visual acuity was evaluated for at least 90 days after surgery, and BAD data (ART-Max and BAD-D) were correlated with final VA. ART-Max values of <339, 339 to 424, and >424 were considered abnormal, borderline, and normal, respectively. Abnormal and borderline values were rated as abnormal. BAD-D scores >1.6 were considered abnormal, as reported by Valbon et al. (5) Data were obtained from medical records and stored in the BAD database. BAD-D data were correlated with parameters described in the literature. (5,6) The inclusion criteria were patients with normal corneal topography who underwent Pentacam examination in the preoperative period (routine procedure in our institution for premium lens implantation) and later underwent cataract surgery with premium IOL implantation. Eyes with unsatisfactory final VA were excluded from the analysis because residual refractive errors in this group were incompatible with VA of 20/25 or higher. Only VA was analyzed rather than patient satisfaction because some patients have no satisfaction after the surgery, even without residual refractive error, normal cornea, and normal macula, but due to the technology itself. The study did not check AV and reading speed closely.
Statistical comparisons between the groups with normal and abnormal ART-Max and BAD-D values and comparisons of VA between the groups were performed using the chi-square test with a 95% confidence interval.

RESULTS
During the study period, cataract surgery with premium IOL implantation was performed in 110 eyes. Seven (6.36%) eyes with VA of less than 20/25 were excluded from the analysis because the residual refractive errors in this group were incompatible with VA of 20/25 or higher.

DISCUSSION
Since the development of the anterior corneal topography, new technologies have emerged to improve tomographic and biomechanical measurements and to diagnose high-order aberrations of the optical system. Variables generated by advanced analytical techniques improve the diagnosis and prognosis of keratoconus and other ectatic diseases, surgical planning, and follow-up. (6) Pentacam corneal tomography, especially outsid the exclusion zone, is useful to evaluate IOL parameters and prevent ectasia. (7) Posterior corneal measurements should be considered for toric IOL calculation and early detection of keratoconus. (8) A study using Pentacam found that the posterior cornea was altered by more than 0.5 D in 12.96% of the eyes of patients who underwent cataract surgery, and this factor affected the measurement of total corneal astigmatism and aberration. (9) Corneal ectasia is a well-known complication of LASIK, and missed diagnosis before LASIK surgery is a significant risk factor for developing ectatic disease postoperatively. Posterior corneal elevation is an early sign of keratoconus. Therefore, it is essential to measure the posterior corneal curvature and BAD-D in each candidate for LASIK.
The use of laser refractive surgery instead of more complex procedures, such as Piggyback IOL implantation or IOL replacement, given its convenience and efficacy, can effectively correct residual refractive errors. (1) BAD-D and ART-Max can accurately detect corneal abnormalities before the occurrence of significant topographical changes. (10) BAD-D scores should be interpreted together with clinical history and topographic and biomechanical data. (11) However, patients with posterior corneal elevation and abnormal BAD-D or ART-Max are not good candidates for refractive surgery because refractive correction increases the risk of corneal ectasia.
Eyes with abnormal BAD-D or ART-Max and normal corneal topography were included in this study. However, AV and reading speed were not checked closely. ART-Max values were abnormal in most eyes with normal corneal topography and good VA (20/25 or 20/20), and 3.63% were excluded from the study because they had an abnormal ART-Max and BAD-D with VA below 20/25. A good surgical  outcome regarding VA eliminates the need for refractive correction and underscores the importance of performing topographical examinations before cataract surgery. Although premium IOL implantation is contraindicated in patients with corneal abnormalities based on BAD-D and ART-Max results, these parameters did not affect final VA, despite the higher number of patients with abnormal values. Therefore, this recommendation was not applicable due to the reduced need for refractive correction in these cases. Our objective was just to show that even with these abnormal values, the result regarding VA were great and, in this population, its more common to have abnormal ART-Max and BAD-D values, so it does not tend to be a contra-indication for IOL premium implantation.
The difference in BAD-D was not significant between the study groups (p=0.9576). Therefore, good final VA was not dependent on BAD-D, supporting the indication of cataract surgery with premium IOL implantation, even in cases in which BAD-D values were abnormal.

CONCLUSION
Patients with normal corneal topography and abnormal ART-Max before cataract surgery and premium intraocular lens implantation had good surgical outcomes and final visual acuity. Despite the higher number of patients with abnormal ART-Max values, both groups achieved a visual acuity of 20/20 and 20/25, eliminating the need for refractive surgery. The percentage of patients with final visual acuity of 20/20 or 20/25 was similar between the groups with high and low BAD-D.
The results showed that normal topography of the anterior cornea, even in the presence of posterior corneal curvature changes assessed by Pentacam, was a good parameter for selecting patients for premium intraocular lens implantation.
Abnormal ART-Max and BAD-D values were common in patients with normal corneal topography who underwent premium intraocular lens implantation and had good final visual acuity, providing evidence that it possibly should not be a contraindication. However, other studies to analyze the quality of vision and satisfaction are necessary.