Elie Zaher, Yonatan Blumenthal, Eytan Z Blumenthal
{"title":"The lack of floater perception in eyes with asteroid hyalosis and its direct implications on laser vitreolysis.","authors":"Elie Zaher, Yonatan Blumenthal, Eytan Z Blumenthal","doi":"10.1186/s40942-024-00601-0","DOIUrl":null,"url":null,"abstract":"<p><strong>Purpose: </strong>To present a novel optical model explaining why the vast majority of patients with Asteroid Hyalosis (AH) do not perceive any floaters. This changes our understanding of floater perception and undermines the operation mode of YAG laser vitreolysis.</p><p><strong>Methods: </strong>Relying on a previously published model of floater perception based on astronomical equations of a solar eclipse, and on ultrasound images of the vitreous in three eyes with AH, we explain why such patients do not perceive floaters in spite of opaque bodies filling their entire vitreous, to the point of, in severe cases of AH, obscuring the fundus view during ophthalmoscopy.</p><p><strong>Main outcome measures: </strong>Developing an optical model of light rays that can quantify the maximal distance upon which a vitreous floater or opacity will cast a shadow on the retina.</p><p><strong>Results: </strong>Calculations using the proposed model demonstrated that with a 3 mm pupil, for a floater located between 1.5 mm and 2 mm from the retina, its shortest diameter must be > 215 microns and > 286 microns, respectively, to be perceived. Since AH floaters, based on ultrasound imaging, do not exist in the most peripheral 1.5 mm of the vitreous, it becomes understandable why these patients are asymptomatic.</p><p><strong>Conclusions: </strong>Based on the proposed model and our findings, we deduced that even large, degenerative floaters whose width is usually narrower than a large retinal vein (125 microns), must be located very close to the retina and hence are not the floaters that are aimed at when performing YAG laser vitreolysis. We speculate that in successful cases, YAG vitreolysis works by a different mechanism, most likely a shock wave that displaces floaters further away from the retina. Hence, vitreolysis might not necessarily require the laser be aimed at the floaters, as symptomatic floaters may be located in the outer 1.5-2.0 mm of the vitreous body, a very risky zone for YAG laser shots.</p>","PeriodicalId":14289,"journal":{"name":"International Journal of Retina and Vitreous","volume":"10 1","pages":"80"},"PeriodicalIF":1.9000,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11515566/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"International Journal of Retina and Vitreous","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1186/s40942-024-00601-0","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"OPHTHALMOLOGY","Score":null,"Total":0}
引用次数: 0
Abstract
Purpose: To present a novel optical model explaining why the vast majority of patients with Asteroid Hyalosis (AH) do not perceive any floaters. This changes our understanding of floater perception and undermines the operation mode of YAG laser vitreolysis.
Methods: Relying on a previously published model of floater perception based on astronomical equations of a solar eclipse, and on ultrasound images of the vitreous in three eyes with AH, we explain why such patients do not perceive floaters in spite of opaque bodies filling their entire vitreous, to the point of, in severe cases of AH, obscuring the fundus view during ophthalmoscopy.
Main outcome measures: Developing an optical model of light rays that can quantify the maximal distance upon which a vitreous floater or opacity will cast a shadow on the retina.
Results: Calculations using the proposed model demonstrated that with a 3 mm pupil, for a floater located between 1.5 mm and 2 mm from the retina, its shortest diameter must be > 215 microns and > 286 microns, respectively, to be perceived. Since AH floaters, based on ultrasound imaging, do not exist in the most peripheral 1.5 mm of the vitreous, it becomes understandable why these patients are asymptomatic.
Conclusions: Based on the proposed model and our findings, we deduced that even large, degenerative floaters whose width is usually narrower than a large retinal vein (125 microns), must be located very close to the retina and hence are not the floaters that are aimed at when performing YAG laser vitreolysis. We speculate that in successful cases, YAG vitreolysis works by a different mechanism, most likely a shock wave that displaces floaters further away from the retina. Hence, vitreolysis might not necessarily require the laser be aimed at the floaters, as symptomatic floaters may be located in the outer 1.5-2.0 mm of the vitreous body, a very risky zone for YAG laser shots.
期刊介绍:
International Journal of Retina and Vitreous focuses on the ophthalmic subspecialty of vitreoretinal disorders. The journal presents original articles on new approaches to diagnosis, outcomes of clinical trials, innovations in pharmacological therapy and surgical techniques, as well as basic science advances that impact clinical practice. Topical areas include, but are not limited to: -Imaging of the retina, choroid and vitreous -Innovations in optical coherence tomography (OCT) -Small-gauge vitrectomy, retinal detachment, chromovitrectomy -Electroretinography (ERG), microperimetry, other functional tests -Intraocular tumors -Retinal pharmacotherapy & drug delivery -Diabetic retinopathy & other vascular diseases -Age-related macular degeneration (AMD) & other macular entities