About

Michael W. Belin, MD is a Professor of Ophthalmology at the University of Arizona's College of Medicine in Tucson. He is affiliated with the Department of Ophthalmology and Vision Science and is based at the Southern Arizona VA Health Care System. His professional focus includes cornea and cataract specialties. Dr. Belin's role involves patient care, research, and education within the field of ophthalmology, contributing to the advancement of ophthalmic medicine through his work at the university and VA healthcare system.

Research topics

• Medicine
• Ophthalmology
• Optometry
• Surgery
• Physics
• Internal medicine
• Pathology

Selected publications

• Visual And Refractive Outcomes Following Laser Blended Vision With Non-Linear Aspheric Micro-Anisometropia (Presbyond)

  2026-03-31

  articleOpen access1st authorCorresponding
  PublisherDOI

• Revised Calculation of the Prevalence of Keratoconus Based on Updated Scheimpflug Corneal Tomography Metrics in a Pediatric Population From a Chicago-Based School Age Vision Clinic

  Eye & Contact Lens Science & Clinical Practice · 2026-01-05

  articleOpen access1st authorCorresponding

  To the Editor: We report an important update to the paper, Harthan JS, Gelles JD, Block SS, et al., Prevalence of Keratoconus Based on Scheimpflug Corneal Tomography Metrics in a Pediatric Population From a Chicago-Based School Age Vision Clinic. Published in Eye and Contact Lens in 2024.1 The original paper studied school age children ages 3 to 18 years and is significant in that the diagnosis of keratoconus was made using modern tomographic parameters and stressed the importance of early diagnosis. Earlier papers on the prevalence of disease commonly used anterior surface topography, which while specific, lacks sensitivity as it identifies disease in the later stages when anterior surface changes occur. This often underestimates the prevalence and does not allow identification of early or subclinical disease where intervention (e.g., corneal crosslinking) can prevent vision loss. The paper initially reported a prevalence of 1:334 for keratoconus and a prevalence of 1:223 when keratoconus suspects were included. Tomographic criteria for keratoconus included a final “D” from the Belin/Ambrósio display (Pentacam, OCULUS GmbH, Wetzlar, Germany) ≥3.02 and a posterior elevation at the corneal thinnest point ≥18 μm for myopic individuals and ≥28 μm for hyperopic patients. Prevalence rates were reported by subject if one or both eyes met criteria. The same analysis was used in the revised tabulation. The Belin/Ambrósio display was initially developed to screen patients for refractive surgery, and the final “D” represents variance from normal, but, in itself, is not specific for ectatic disease (e.g., corneal edema will result in an elevated final “D”). Typically, additional tomographic parameters, in addition to the final “D,” are included to improve specificity for keratoconus. These additional parameters may include an abnormal pachymetric progression and/or posterior elevation at the thinnest point (as in this study). Most of the confounding conditions, such as endothelial dysfunction, occur in adults and confounding conditions in children (e.g., congenital hereditary endothelial dystrophy) would be readily apparent. The goal of adding additional parameters is to improve specificity but should not be so restrictive as to decrease sensitivity. The values for the posterior elevation at the thinnest point chosen by the authors represent values 3.0 SD from the norm, which when added to the final “D” ≥3.0 become overly restrictive.3 In collaboration with the original authors and after the original publication, it was agreed that the results should be retabulated using the same final “D” (≥3.0), but with values for the posterior elevation at the thinnest point of 13 and 23 μm (myopic/hyperopic) roughly corresponding to 2 SD.4,5 This change should not significantly alter the overall specificity but should decrease false negatives. Prior studies showed that a final “D” ≥2.69 had a 100% specificity for keratoconus in an adult population when other known pathologies were excluded. How this compares to a pediatric population is not known as most studies dealt with a refractive surgery population.4 The revised parameters defined keratoconus as a final “D” ≥3.0 with a posterior elevation at the thinnest point ≥13/23 μm for myopic and hyperopic eyes, respectively. Suspect included eyes with a final “D” ≥2.0 but <3.0 with the same posterior elevation parameters. Normal eyes had a final “D” <2.0. With these adjusted parameters, the revised prevalence of keratoconus in the study population of 2007 individuals is 1:251 (an increase from six to eight classified as keratoconus), the prevalence of keratoconus suspect is 1:100 (an increase from 3 to 20), and the prevalence when combining keratoconus and keratoconus suspects is 1:72 (an increase from 9 to 28). Keratoconus is a visually disabling disorder that if left untreated or if treated late can lead to permanent, life-long debility. Using modern corneal imaging, the old historical teaching of keratoconus as a rare disease no longer applies. Early diagnosis is paramount if one wishes to intervene before significant visual loss. Since keratoconus typically first becomes evident in the pediatric age group knowledge of the disease, its diagnosis and treatment options need to be known not only by ophthalmologist and optometrists but by pediatricians, family practitioners, and school health screeners. The paper cited above, along with the even higher prevalence rates presented here, stresses the importance of keratoconus screening using modern diagnostic modalities. In addition to the use of Scheimpflug corneal tomography, advances in optical coherence tomography and biomechanical assessment may further enhance sensitivity and specificity in the detection of keratoconus and keratoconus suspects. We hope to increase awareness of the prevalence of the disease along with the goal of identifying disease early to limit future vision loss.

  PublisherDOI

• Guide to Pentacam Interpretation for Keratoconus and Corneal Ectasia

  Cornea Open · 2025-12-01

  articleOpen accessSenior author

  Purpose: The Pentacam, a Scheimpflug-based tomographic device, is an invaluable tool for identifying corneal diseases. The purpose of this review was to explain the data and images available on the 4 Maps Refractive , Belin/Ambrósio Enhanced Ectasia (BAD display) , and the Belin ABCD Progression Display. Methods: From the Pentacam manual, published literature, and expert knowledge, details of each report were synthesized. Results: A comprehensive explanation of the values and figures for the above listed displays. Conclusions: The Pentacam measures and provides an abundance of data for the cornea and anterior segment. Through this information, clinicians can better diagnose and identify progression of corneal ectasia and keratoconus and effectively screen refractive surgery patients.

  PublisherDOI

• Pressure-Induced Stromal Keratitis and Persistent Epithelial Defect (PED) Masquerade Syndrome

  2025-01-01

  book-chapter
  PublisherDOI

• Predictive value of enhanced corneal biomechanical parameters for ectasia progression

  Japanese Journal of Ophthalmology · 2025-01-20 · 2 citations

  articleOpen access

  PURPOSE: To determine whether corneal biomechanical parameters can predict ectasia progression. STUDY DESIGN: Retrospective observational study. METHODS: The baseline corneal biomechanical parameters of 64 eyes of 41 young patients (age, < 25 years at the first visit) who were diagnosed with keratoconus (KC) or suspected KC at Osaka University Hospital and followed up for more than two years were reviewed. Suspected KC was defined as borderline cases with no definitive clinical or topographical abnormalities in both eyes. The eyes were divided into progressed (P) and non-progressed (NP) groups using the ABCD grading system of Scheimpflug-based tomography. The Scheimpflug-based corneal biomechanical parameters evaluated included deformation amplitude ratio within 2 mm, integrated radius, Ambrósio relational thickness to the horizontal profile, stiffness parameter at the first applanation, stress-strain index, E-staging, and Corvis Biomechanical Index. The optimized tomographic/biomechanical index (TBIv2), Belin/Ambrósio Enhanced Ectasia Deviation (BAD-D), and inferior-superior axial steepening values from Scheimpflug-based tomography were also evaluated. RESULTS: Twenty-three and 41 eyes were categorized into the P and NP groups, respectively. Logistic regression analysis showed that age, BAD-D, and TBIv2 could predict ectasia progression. The specificity, sensitivity, and area under the receiver operating characteristic curve (AUROC) values for BAD-D combined with age were 0.82, 0.60, and 0.83, respectively, whereas those for TBIv2 combined with age were 0.65, 0.82, and 0.82, respectively. CONCLUSIONS: Baseline TBIv2 is a potentially useful predictive marker for ectasia progression in young patients, whereas baseline BAD-D could be used for establishing a definitive diagnosis.

  PublisherOA PDFDOI

• Ectasia screening with the pentacam scheimpflug tomographer: the belin ambrosio module

  Acta Ophthalmologica · 2025-01-01

  article1st authorCorresponding

  Screening for ectatic disease falls into two general categories; 1) refractive surgery screening, where the goal is to identify patients at potential risk for post‐refractive ectasia, and 2) identifying patients with true ectatic disease (keratoconus) at the earliest possible point in the disease process to intervene to limit and/or prevent sequalae. Tomographic imaging (either Scheimpflug or OCT) allows for the earliest detection of disease by its ability to image all anterior segment surfaces. The Belin/Ambrosio Display (BAD) utilizes 9 different tomographic parameters in a proprietary regression formula and was designed to fulfill both functions (screening &amp; diagnosis). The differences, however, are important. The overall reading of the BAD is done by the final “D”. The final “D” represents variance from normal, but not necessarily keratoconus. The BAD display will show an elevated final “D” in any corneal condition that varies from normal. Conditions such as corneal edema or post refractive surgery will produce an elevated final “D” as these conditions differ from the normal cornea. Diagnosing keratoconus requires identifying those parameters that are specific for keratoconus that in addition to the final “D”, raises the specificity for keratoconus. A current FDA Phase 3 protocol looks at posterior elevation at the thinnest point, and a Percent Thickness Increase (PTI) graph with the tracing below midline. These parameters added to a specified final “D” would increase disease specificity. The BAD display has been shown to have both high sensitivity and specificity, but screening values can be adjusted to suit the clinical or study situation.

  PublisherDOI

• Effect of Astigmatism Treatment With Three Excimer Lasers After Photorefractive Keratectomy

  Eye & Contact Lens Science & Clinical Practice · 2024-07-09

  article

  OBJECTIVES: To compare astigmatism correction after photorefractive keratectomy (PRK) using three excimer laser devices, Alcon Wavelight EX500, Schwind Amaris 1,050, and Technolas Teneo317 M2. METHODS: This retrospective study included 414 eyes from 414 subjects with a history of PRK performed using Alcon Wavelight (n=172), Schwind Amaris (n=122), and Technolas (n=120). Uncorrected & corrected distance visual acuity (UDVA & CDVA), and refractive status (spherical equivalent (SE) and vector analysis (J0 and J45)) were postoperatively recorded at the 6-month and 12-month examinations. RESULTS: The mean CDVA and J45 at 6-month and 12-month showed no statistically significant difference among the three different excimer lasers ( P >0.05). There was a statistically significant difference in mean UDVA and J0 at 6-month and 12-month after PRK among the three groups, with no statistically significant difference between Alcon Wavelight and Schwind Amaris lasers, while both of the prior lasers showed a significant difference with the Technolas laser. The highest and lowest changes in the magnitude of J0 in 6-month and 12-month follow-ups were seen for the Alcon Wavelight and Technolas groups, respectively. Both Schwind Amaris and Technolas had a small hyperopic SE while the Alcon Wavelight's SE was minimally myopic. This difference in SE between Alcon Wavelight and both Schwind Amaris and Technolas reached statistical significance. CONCLUSION: While all three lasers performed well in reducing preoperative astigmatism; however, the Alcon Wavelight and Schwind Amaris were more effective in correcting astigmatism than the Technolas. The difference between the Alcon Wavelight and Schwind Amaris did not reach statistical significance.

  PublisherDOI

• The biomechanical e‐staging—In vivo assessment of corneal biomechanics in keratoconus

  Acta Ophthalmologica · 2024-01-01

  article

  Aims/Purpose: Keratoconus (KC) is biomechanically characterized by a decreased resistance to deformation when compared to healthy corneas. The aim of this presentation is to give an overview about the development and clinical application of the recently introduced Homburg Biomechanical E‐Staging (BEST) for KC. Methods: The Corvis ST (Oculus, Germany) non‐contact pneumotonometer measures the corneal deformation after applying a standardized air puff. It calculates the quasi‐binary indices Corvis Biomechanical Index (CBI) and Tomographic Biomechanical Index (TBI) to separate healthy from ectatic corneas, without, however providing a biomechanical KC severity stage. The Homburg BEST based on the linearized CBI provides information about biomechanical KC severity in form of E‐stages 0 to 4, thus augmenting the existing tomographic ABCD KC classification by including corneal biomechanics. Several studies and results about the development and clinical application of the Homburg BEST are presented. Results: The Homburg BEST was developed based on two independent KC datasets (Homburg: n = 448, Milano/Rio: n = 860). Since 2022, it has been integrated into the Corvis ST software, thus providing a biomechanical KC severity and progression assessment. The software based on several individual biomechanical parameters indicates KC progression like tomographic progression parameters. However, it is influenced by corneal thickness measurements, increases within the first postoperative months after corneal crosslinking (CXL) and indicates postoperative KC stabilization more than 1 year after CXL. Intracorneal ring segment implantation permanently affects corneal thickness in the midperiphery and contributes to slightly higher postoperative BEST values. Conclusions: Although with limitations, the Homburg BEST enables a biomechanical staging and progression assessment in KC by considering several biomechanical parameters as an addition to the previously purely tomographic or even topographic analysis.

  PublisherDOI

• Comparison of corneal biomechanical parameters in healthy corneas with symmetric and asymmetric bow-tie topographic pattern with inferior and superior steepening

  International Ophthalmology · 2024-02-07

  article
  PublisherDOI

• Policy, Position, and Research Subcommittee Review of HTLV-1 and HTLV-2 Serologic Testing

  Eye Banking and Corneal Transplantation · 2024-05-28 · 2 citations

  articleOpen accessCorresponding

  In Brief This document provides information to assist the Medical Advisory Board of the Eye Bank Association of American (EBAA) in re-evaluating the clinical utility of serologic testing for human T-lymphotropic viruses type I and type II (HTLV-I and HTLV-II) and to assist in the determination of whether t HTLV testing is applicable and indicated for selection of donors of ocular tissue.

  PublisherDOI

Frequent coauthors

• Renato Ambrósio

  68 shared

• Alvin L. Young

  Prince of Wales Hospital

  32 shared

• Ka Wai Kam

  Chinese University of Hong Kong

  32 shared

• Joseph B. Ciolino

  Harvard University

  30 shared

• Stephen S. Khachikian

  24 shared

• Riccardo Vinciguerra

  18 shared

• Paolo Vinciguerra

  IRCCS Humanitas Research Hospital

  17 shared

• Bernardo T. Lopes

  Alder Hey Children's NHS Foundation Trust

  17 shared

Labs

• McKay LabPI