Refractive Changes Following CXL
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Refractive Error Changes in Cortical, Nuclear and Posterior Subcapsular Cataracts
1524 Refractive error changes in cortical, nuclear and posterior subcapsular cataracts. D.B. Elliott & K. Pesudovs . Department of Optometry, University of Bradford, Bradford, United Kingdom.. Purpose • To determine the effect of the three main morphological types of age-related cataract on refractive error. Background • The increase in myopia in some patients with age-related nuclear cataract is well known (Brown & Hill, 1987). This change accounts for the “second sight of the elderly” in which the myopic shift provides normal reading ability without the need for spectacles. Distance vision, however, worsens. • Planter (1981) suggested that cortical opacity can induce hyperopic shifts. However, this claim has not been repeated since and no firm evidence is available. • Review papers suggest that cortical opacity can induce astigmatic changes (Brown, 1993). However, these reports were based on clinical impression with no supporting data. • . The prevalence of uncorrected refractive error in the elderly population is high (Wormald et al., 1992). It is likely that a reasonable proportion of these patients have refractive error changes induced by cataract. • It has been suggested that a delay in operating on age-related cataract of 10 years could reduce the number of patients requiring cataract surgery (Kupfer, 1985). The possible role of correcting cataract-induced refractive error to delay the need for surgery should be explored. Subjects • 98 elderly subjects (mean age 67 ± 8 years) were recruited. • 77 subjects had one type of morphological cataract: 34 subjects had cortical cataract, 21 had nuclear cataract and 21 had posterior subcapsular cataract (PSC). • 22 subjects had normal, healthy eyes. • Ocular screening excluded amblyopia, strabismus, eye disease or surgery. -
Fact Sheet: Refractive Errors
Fact Sheet: Refractive Errors More than 11 million Americans have common vision problems that can be corrected with the use of prescriptive eyewear such as glasses or contact lenses.1 These conditions are known as refractive errors and they occur when the eye doesn’t correctly bend, or ―refract,‖ light as it enters the eye. Common refractive errors include the following: o Nearsightedness (also called myopia)—A condition where objects up close appear clearly, while objects far away appear blurry. With nearsightedness, light comes to focus in front of the retina instead of on the retina. o Farsightedness (also called hyperopia)—A common type of refractive error where distant objects may be seen more clearly than objects that are near. However, people experience farsightedness differently. Some people may not notice any problems with their vision, especially when they are young. For people with significant farsightedness, vision can be blurry for objects at any distance, near or far. o Astigmatism—A condition in which the eye does not focus light evenly onto the retina, the light-sensitive tissue at the back of the eye. This can cause images to appear blurry and stretched out. o Presbyopia—An age-related condition in which the ability to focus up close becomes more difficult. As the eye ages, the lens can no longer change shape enough to allow the eye to focus close objects clearly. Refractive errors are one of the most common—and correctable—causes of visual impairment in the United States. According to a recent study led by the National Eye Institute (NEI), approximately half of all American adults don’t have the 20/20 vision physicians consider optimal due to refractive errors.2 Women experience refractive error more frequently than men: Twenty-six percent more women aged 12 and older have uncorrected visual impairment due to refractive error compared with men aged 12 and older. -
Hyperopia Hyperopia
Hyperopia Hyperopia hyperopia hyperopia • Farsightedness, or hyperopia, • Farsightedness occurs if your eyeball is too as it is medically termed, is a short or the cornea has too little curvature, so vision condition in which distant objects are usually light entering your eye is not focused correctly. seen clearly, but close ones do • Its effect varies greatly, depending on the not come into proper focus. magnitude of hyperopia, the age of the individual, • Approximately 25% of the the status of the accommodative and general population is hyperopic (a person having hyperopia). convergence system, and the demands placed on the visual system. By Judith Lee and Gretchyn Bailey; reviewed by Dr. Vance Thompson; Flash illustration by Stephen Bagi 1. Cornea is too flap. hyperopia • In theory, hyperopia is the inability to focus and see the close objects clearly, but in practice many young hyperopics can compensate the weakness of their focusing ability by excessive use of the accommodation functions of their eyes. Hyperopia is a refractive error in • But older hyperopics are not as lucky as them. By which parallel rays of light aging, accommodation range diminishes and for 2. Axial is too short. entering the eye reach a focal older hyperopics seeing close objects becomes point behind the plane of the retina, while accommodation an impossible mission. is maintained in a state of relaxation. 1 Amplitude of Accommodation hyperopia Maximum Amplitude= 25-0.4(age) • An emmetropic eye for reading and other near Probable Amplitude= 18.5-.3(age) work, at distance of 16 in (40cm), the required amount of acc. -
Myopia: More Than a Refractive Error − Lasik and Retinal Dystrophies
MYOPIA: MORE THAN A REFRACTIVE ERROR − LASIK AND RETINAL DYSTROPHIES WALRAEDT S.1*, LEROY B.P.1,2*, KESTELYN P.H.1, DE LAEY J.J.1 SUMMARY SAMENVATTING Three patients who had undergone laser in situ Drie patiënten die een correctie van myopie hadden keratomileusis (LASIK) correction for myopia were ondergaan met laser in situ keratomileusis (LASIK) first seen because of suboptimal visual acuity (VA) werden onderzocht omwille van postoperatieve sub- and night blindness and/or photophobia. After a com- optimale visus en nachtblindheid en/of fotofobie. Na prehensive examination including psychophysical uitgebreid onderzoek met inbegrip van psychofysi- and electrophysiological tests, two of the three pa- sche en electrofysiologische testen werd een dia- tients were shown to suffer from a progressive cone- gnose van progressieve kegeltjes-staafjesdystrofie ge- rod dystrophy. The third patient had retinitis pig- steld bij twee patiënten. De derde patiënt leed aan mentosa. These cases illustrate the need for in depth retinitis pigmentosa. Deze gevallen illustreren de preoperative evaluation in myopic patients about to noodzaak van een doorgedreven preoperatief onder- undergo LASIK when signs or problems of night blind- zoek bij myope patiënten die LASIK zullen onder- ness and/or photophobia are present. gaan met klachten van nachtblindheid en fotofobie. KEY WORDS RÉSUMÉ Retinal dystrophy, cone-rod dystrophy, Trois patients sont présentés ayant été examinés pour retinitis pigmentosa, photophobia, night une acuité visuelle sous-optimale et une héméralo- blindness, laser in situ keratomileusis, pie et/ou photophobie, après correction d’une myo- preoperative evaluation pie suivant la technique du laser in situ keratomi- leusis (LASIK). Sur base d’une évaluation élaborée, MOTS-CLÉS y inclus des tests psychophysiques et éléctrophysio- logiques, un diagnostic de dystrophie des cônes et Dystrophie rétinienne, dystrophie de type bâtonnets a été établi chez deux patients. -
Management Modalities for Keratoconus an Overview of Noninterventional and Interventional Treatments
REFRACTIVE SURGERY FEATURE STORY EXCLUSIVE ONLINE CONTENT AVAILABLE Management Modalities for Keratoconus An overview of noninterventional and interventional treatments. BY MAZEN M. SINJAB, MD, PHD anagement of keratoconus has advanced TAKE-HOME MESSAGE during the past few years, and surgeons can • When evaluating patients with keratoconus, ask now choose among numerous traditional and them to stop using RGP contact lenses at least 2 modern treatments. Traditional modalities weeks before evaluation to achieve correct Msuch as spectacle correction, contact lenses, penetrating measurement of the corneal shape. keratoplasty (PKP), and conductive keratoplasty (CK) • Interventional management modalities include CK, are still effective; however, demand for the last two has PKP, DALK, ICRSs, CXL, phakic IOLs, or some decreased with the advent of modern alternatives, specifi- combination of these treatments. cally intrastromal corneal ring segments (ICRSs) and cor- • Making the right management decision depends neal collagen crosslinking (CXL). Caution should be used on the patient’s corneal transparency and stress when considering these newer treatment modalities, and lines, age, progression, contact lens tolerance, surgeons should be aware of their indications, contraindi- refractive error, UCVA and BCVA, K-max, corneal cations, conditions, and complications before proceeding thickness, and sex. with treatment. Keratoconus treatments can be divided into two cate- Some patients achieve good vision correction and comfort gories, interventional and noninterventional. In this article, with this strategy. particular attention is given to ICRSs and CXL, as they are Advances in lens designs and materials have increased the the most popular emerging interventional management proportion of keratoconus patients who can be fitted with modalities for keratoconus. -
Cone Contributions to Signals for Accommodation and the Relationship to Refractive Error
Vision Research 46 (2006) 3079–3089 www.elsevier.com/locate/visres Cone contributions to signals for accommodation and the relationship to refractive error Frances J. Rucker ¤, Philip B. Kruger Schnurmacher Institute for Vision Research, State University of New York, State College of Optometry, 33 West 42nd Street, New York, NY 10036, USA Received 18 February 2005; received in revised form 7 April 2006 Abstract The accommodation response is sensitive to the chromatic properties of the stimulus, a sensitivity presumed to be related to making use of the longitudinal chromatic aberration of the eye to decode the sign of the defocus. Thus, the relative sensitivity to the long- (L) and middle-wavelength (M) cones may inXuence accommodation and may also be related to an individual’s refractive error. Accommodation was measured continuously while subjects viewed a sine wave grating (2.2 c/d) that had diVerent cone contrast ratios. Seven conditions tested loci that form a circle with equal vector length (0.27) at 0, 22.5, 45, 67.5, 90, 120, 145 deg. An eighth condition produced an empty Weld stimulus (CIE (x,y) co-ordinates (0.4554, 0.3835)). Each of the gratings moved at 0.2 Hz sinusoidally between 1.00 D and 3.00 D for 40 s, while the eVects of longitudinal chromatic aberration were neutralized with an achromatizing lens. Both the mean level of accommo- dation and the gain of the accommodative response, to sinusoidal movements of the stimulus, depended on the relative L and M cone sen- sitivity: Individuals more sensitive to L-cone stimulation showed a higher level of accommodation (p D 0.01; F D 12.05; ANOVA) and dynamic gain was higher for gratings with relatively more L-cone contrast. -
Refractive Changes After Scleral Buckling Surgery
Refractive changes after scleral buckling surgery Alterações refracionais após retinopexia com explante escleral João Jorge Nassaralla Junior1 ABSTRACT Belquiz Rodriguez do Amaral Nassaralla2 Purpose: A prospective study was conducted to compare the refractive changes after three different types of scleral buckling surgery. Methods: A total of 100 eyes of 100 patients were divided into three groups according to the type of performed buckling procedure: Group 1, encircling scleral buckling (42 patients); Group 2, encircling with vitrectomy (30 patients); Group 3, encircling with additional segmental buckling (28 patients). Refractive examinations were performed before and at 1, 3 and 6 months after surgery. Results: Changes in spherical equivalent and axial length were significant in all 3 groups. The amount of induced astigmatism was more significant in Group 3. No statistically significant difference was found in the amount of surgically induced changes between Groups 1 and 2, at any postoperative period. Conclusions: All three types of scleral buckling surgery were found to produce refractive changes. A correlation exists between additional segments and extent of refractive changes. Keywords: Retinal detachment/surgery; Scleral buckling/adverse effects; Refraction/ ocular; Biometry INTRODUCTION During the past several years, our Retina Service and others(1) have continued to use primarily solid implants with encircling bands. Only occa- sionally episcleral silicone rubber sponges are utilized. Changes in refrac- tion are frequent after retinal detachment surgery. The surgical technique used appears to influence these changes. Hyperopia(2) and hyperopic astig- matism may occur presumably by shortening the anteroposterior axis of the globe after scleral resections(1). Scleral buckling procedures employing an encircling band generally are expected to produce an increase in myopia and myopic astigmatism(1,3). -
Refractive Errors a Closer Look
2011-2012 refractive errors a closer look WHAT ARE REFRACTIVE ERRORS? WHAT ARE THE DIFFERENT TYPES OF REFRACTIVE ERRORS? In order for our eyes to be able to see, light rays must be bent or refracted by the cornea and the lens MYOPIA (NEARSIGHTEDNESS) so they can focus on the retina, the layer of light- sensitive cells lining the back of the eye. A myopic eye is longer than normal or has a cornea that is too steep. As a result, light rays focus in front of The retina receives the picture formed by these light the retina instead of on it. Close objects look clear but rays and sends the image to the brain through the distant objects appear blurred. optic nerve. Myopia is inherited and is often discovered in children A refractive error means that due to its shape, your when they are between ages eight and 12 years old. eye doesn’t refract the light properly, so the image you During the teenage years, when the body grows see is blurred. Although refractive errors are called rapidly, myopia may become worse. Between the eye disorders, they are not diseases. ages of 20 and 40, there is usually little change. If the myopia is mild, it is called low myopia. Severe myopia is known as high myopia. Lens Retina Cornea Lens Retina Cornea Light rays Light is focused onto the retina Light rays Light is focused In a normal eye, the cornea and lens focus light rays on in front of the retina the retina. In myopia, the eye is too long or the cornea is too steep. -
Demographic Pattern of Refractive Anomalies in Niger Delta Presbyopes - Implications for Preventive Eye Care Practice
Research Article More Information *Address for Correspondence: Ireju Onyinye Demographic pattern of refractive Chukwuka, Department of Ophthalmology, College of Health Sciences, University of Port Harcourt, Nigeria, Tel: +234-8033103817; Email: anomalies in Niger Delta presbyopes [email protected]; [email protected] Submitted: 07 January 2020 - Implications for preventive eye care Approved: 28 January 2020 Published: 29 January 2020 How to cite this article: Ireju Onyinye Chukwuka, practice Chinyere Nnenne Pedro-Egbe. Demographic pattern of refractive anomalies in Niger Delta Ireju Onyinye Chukwuka* and Chinyere Nnenne Pedro-Egbe presbyopes-Implications for preventive eye care practice. Int J Clin Exp Ophthalmol. 2020; 4: Department of Ophthalmology, College of Health Sciences, University of Port Harcourt, Nigeria 005-008. DOI: dx.doi.org/10.29328/journal.ijceo.1001025 Abstract Copyright: © 2020 Ireju Onyinye Chukwuka and Chinyere Nnenne Pedro-Egbe. This is an open access article distributed under the Creative Background/Aim: In spite of global initiatives to provide sight for all by the year 2020, many Commons Attribution License, which permits middle-aged to elderly people in the Niger Delta still have signifi cant visual impairment due to unrestricted use, distribution, and reproduction uncorrected refractive errors. The aim of this study is to assess the types of refractive anomalies in any medium, provided the original work is that occur among presbyopic patients in Port Harcourt and determine the demographic pattern properly cited. of these anomalies based on age and gender characteristics. Keywords: Refractive anomalies; Presbyopia; Methodology: This is a hospital-based descriptive cross-sectional study in which sixty Port Harcourt; Nigeria consecutive adult patients for refraction were seen. -
CLINICAL FINDINGS and MANAGEMENT of PELLUCID MARGINAL DEGENERATION USING SCLERAL LENSES OVER INTACS and CORNEAL COLLAGEN CROSS-LINKING with RIBOFLAVIN by Brad T
Case Study CLINICAL FINDINGS AND MANAGEMENT OF PELLUCID MARGINAL DEGENERATION USING SCLERAL LENSES OVER INTACS AND CORNEAL COLLAGEN CROSS-LINKING WITH RIBOFLAVIN By Brad T. Cunningham, OD, FSLS About the Author Dr. Brad Cunningham graduated from New England College of Optometry in 2007 and has been serving the United States Army Medical Service Corps ever since. He completed his primary care and contact lens residency from the University of Incarnate Word, Rosenberg School of Optometry and gained his fellowship in scleral lenses (FSLS) in 2017. Correspondence may be directed to Brad Cunningham: [email protected] Submitted: September 27, 2017. Accepted: December 13, 2017. Published: January 19, 2018. ABSTRACT This case study provides an analysis of an individual affected by pellucid marginal degeneration (PMD). This particular case demonstrates the effectiveness of new scleral lenses over a severe form of PMD that underwent corneal crosslinking (CXL) with riboflavin over intra-stromal corneal ring segments (INTACS). PMD is a rare, progressive, degenerative corneal disease typically characterized as peripheral, bilateral, and inferior ectasia producing a crescent shape. It has been found more commonly in males and appears between the second and fifth decade of life showing no signs of ethnic predilection. Although there is no evidence of the prevalence and etiology of PMD, it may be postulated that PMD is poorly differentiated because this disease is often confused or used interchangeably with keratoconus (KC). KC is a develop- mental anomaly in which a part of the cornea becomes thinner and bulges forward in a cone-shaped fashion as a result of non-inflammatory stromal thinning. -
Name of Condition: Refractive Errors
STANDARD TREATMENT GUIDELINES OPTHALMOLOGY Ministry of Health & Family Welfare Govt. of India 1 Group Head Coordinator of Development Team Dr. Venkatesh Prajna Chief- Dept of Medical Education, Aravind Eye Hospitals, Madurai 2 NAME OF CONDITION: REFRACTIVE ERRORS I. WHEN TO SUSPECT/ RECOGNIZE? a) Introduction: An easily detectable and correctable condition like refractive errors still remains a significant cause of avoidable visual disability in our world. A child, whose refractive error is corrected by a simple pair of spectacles, stands to benefit much more than an operated patient of senile cataract – in terms of years of good vision enjoyed and in terms of overall personality development. In developing countries, like India, it is estimated to be the second largest cause of treatable blindness, next only to cataract. Measurement of the refractive error is just one part of the whole issue. The most important issue however would be to see whether a remedial measure is being made available to the patient in an affordable and accessible manner, so that the disability is corrected. Because of the increasing realization of the enormous need for helping patients with refractive error worldwide, this condition has been considered one of the priorities of the recently launched global initiative for the elimination of avoidable blindness: VISION 2020 – The Right to Sight. b) Case definition: i. Myopia or Short sightedness or near sightedness ii. Hypermetropia or Long sightedness or Far sightedness iii. Astigmatism These errors happen because of the following factors: a. Abnormality in the size of the eyeball – The length of the eyeball is too long in myopia and too short in hypermetropia. -
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S Afr Optom 2007 66(2) 77-81 CONFERENCE PAPER Effect of optical defocus on colour perception AO Oduntan٭ RR Sehlapelo and* Department of Optometry, University of Limpopo, Private Bag X1106, Sovenga, 0727 South Africa <[email protected]>٭ Abstract Daily experience shows that colour of a very distant object cannot be accurately determined. It is assumed that visual acuity (VA) loss is one of the factors at play in this case. The effects of reduced VA as a result of refractive error or optical defocus on colour vision have not been examined. Such study will dictate the need or otherwise for optical correction before assessment of colour vision. The purpose of this study therefore, was to investigate the effects of optical defocus on colour vision in individuals with normal colour vision. Twenty nine young adult subjects (11 male and 18 females) were included in this study. Their ages ranged from 11 to 29 years with a mean of 22.1 ± 3.4 years. All subjects had VA of 6/6 or better and normal colour vision. The colour vision was evaluated with the Farnsworth panel D-15 (desaturated). Each subject was optically defocused to VA of 6/24, 6/60 and 1/60 (6/360) at 6 meters respectively and colour vision was assessed at each reduced VA. At VA of 6/24, colour vision was not affected in all subjects. When the VA was reduced to 6/60, however, 15 (51%) of the subjects failed the colour vision test. When the VA was further reduced to 1/60 by optical defocus, 24 (83%) of the subjects failed the colour vision test.