EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/865962
The third refractive surface: Improving surgical outcomes with advanced diagnostics and therapeutics by Christopher Starr, MD Efficiently and accurately diagnosing OSD with advanced tests Once DED is diagnosed, treatment should be based on the underlying DED subtype. Assorted objective tests help differentiate between evaporative and aqueous deficient dry eye. Lipid layer interferometry measures lipid layer thickness, which has been well correlated to dry eye severity and symptoms. It also measures partial blink rate, an often overlooked diagnosis. Meibography helps clinicians identify and grade the severity of meibomian gland disease (Figure 1). It also visually demonstrates the disease to patients, greatly helping patient understanding and acceptance of interventions. it rapidly, and it is reimbursable. If the reading in either eye is 308 mOsms/L or greater or if the inter-eye difference is 8 mOsms/L or greater (even if the value for either eye is less than 308), this indicates tear instability and dry eye (308–320 mOsms/L, mild; 320–340 mOsms/L, moderate; greater than 340 mOsms/L, severe dry eye). The rapid point-of-care MMP-9 test measures ocular surface inflammation levels with high sensitivity and specificity for dry eye disease (DED). Normal osmolarity with elevated MMP-9 may suggest a non-dry eye cause of OSD. Diagnostic challenges make it difficult to choose effective treatments and monitor the patient's response. In addition, patients without symptoms may not accept treatment. Therefore, clinicians need objective sensitive and specific OSD diagnostic tools with a high positive predictive value. Latest OSD diagnostics Ophthalmologists have an array of available objective tests for OSD. The tear osmolarity point- of-care test is noninvasive and objective and correlates strongly with all dry eye levels. It is also useful in monitoring treatment efficacy. Technicians can perform New tests help clinicians diagnose OSD accurately and efficiently I t has been an unprecedent- ed decade in ocular surface disease (OSD) diagnosis. Multiple seminal publi- cations have been published, and new diagnostic tests and treatments have emerged, with expansion of research and devel- opment and a strong pipeline. However, news of these advances may overwhelm or per- plex clinicians seeking the most accurate diagnostics. Diagnostic challenges Dry eye is a complex condition that is often multifactorial. Furthermore, accurate diagnosis may be difficult with traditional means, such as Schirmer's, symp- toms, and signs. The cause of conjunctivitis or common OSD is misdiagnosed in as many as 75% of cases. 1–3 Symptoms, such as itchiness, grittiness, redness, and dryness, overlap in almost all OSD. focusing power. If the tear film is irregular, much larger variations in optical power occur. Variable refractive powers on the ocular surface can lead to higher order aberrations. Image quality is best imme- diately post-blink, but it degrades with rapid disappearance of the tear film. Research has shown that an unstable tear film can increase dry eye symptoms as well as higher order aberrations. Mucin deficiency can lead to a rapid tear breakup time, affect- ing ocular health and vision. Tear film fluctuation may play a major role in determining wavefront aberrations and visual acuity. In addition, cataract surgery causes microscopic ocular surface dam- age contributing to dry eye. Conclusion OSD decreases the predictabili- ty of surgery and postoperative outcomes. The tear film has the greatest optical power of any surface, and a poor tear film leads to poor image quality. There- fore, preoperative diagnosis and treatment of OSD are crucial in every patient to ensure accurate measurements and increase vision quality. References 1. Trattler W, et al. Cataract and dry eye: prospective health assessment of cataract patients' ocular surface study. 2011 ASCRS•ASOA Symposium & Congress. 2. Epitropoulos AT, et al. Effect of tear osmolarity on repeatability of keratometry for cataract surgery planning. J Cataract Refract Surg. 2015;41:1672–7. Dr. Beckman is director of corneal services, Comprehensive EyeCare of Central Ohio, and clinical assistant professor of ophthalmology, Ohio State University, Columbus. He can be contacted at kenbeckman22@aol. com. continued from page 3 Christopher Starr, MD Figure 1. Meibomian gland dropout and attenuation in a patient with symptomatic MGD continued on page 7 4