For small pterygia, simultaneous surgery may not make a difference in the outcome; for larger, visually significant ones, however, sequential surgery can add significant morbidity and recovery time.
The case for sequential surgery. See Three Cases for Sequential Surgery. Large pterygia induce refractive astigmatism, which affects the outcome following cataract surgery.
In eyes with pterygia, corneal topography is more valuable than keratometry because it provides a more detailed picture of the refractive status of the cornea, detecting curvature changes that induce astigmatism.
Large, fleshy pterygia that are vascularized and inflamed change the shape of the cornea. By contrast, small pterygia that have not changed the corneal curvature Figure 1 are best left alone. In these eyes, cataract surgery can be done first, with pterygium excision planned later for refractive correction or cosmesis.
Generally, only pterygia that are more than 3 mm in size cause topographical distortion Figure 2. Postoperative refractive surprises are prevented by ensuring accurate and stable keratometry. The K values used for IOL power calculation will not remain the same following excision of visually significant pterygia.
Thus, when pterygium excision is combined with cataract surgery or performed after cataract surgery, the altered K values cause a refractive surprise. Figure 1. Case No. This patient can undergo cataract surgery without any prior surgical intervention for the pterygium. Figure 2. Although it is difficult to detect the extension of the pterygium into the central cornea on the slit-lamp photo, the Pentacam shows irregular astigmatism of the central cornea induced by the pterygium B.
This patient would benefit from pterygium excision before cataract surgery. Figure 3. Topography shows irregular mires and is not reliable C. Topography is not required in this patient at this time, as pterygium excision is mandatory before cataract surgery. Figure 4. The corneal astigmatism induced by pterygium is often reversible on excision, unless it has caused corneal scarring, as is seen in atrophic ones of long standing.
Large pterygia covering the visual axis Figure 3 must be removed before the cataract surgery. It is impossible obtain a good corneal topography image before excision of these pterygia. Present-day pterygium surgery involves excision of the pterygium followed by gluing of a conjunctival autograft over the bare sclera. Mitomycin C 0. Use of mitomycin C and glued conjunctival autografts may affect outcomes when cataract surgery is combined with pterygium excision.
Thus, it may be better to perform sequential surgery and allow corneal healing to complete before scheduling cataract surgery. As a rule of thumb, any pterygium of 3 mm or greater should be excised before cataract surgery. Patients with irregular mires on keratometry or irregular central curvature or high corneal astigmatism on topography are candidates for primary excision of the pterygium.
Patients with small pterygia at the limbus with regular mires on keratometry, regular central curvature on topography, and low or absent astigmatism can have cataract surgery before pterygium excision.
Following pterygium excision, one should wait 6 to 8 weeks for corneal curvature to stabilize before assessing the patient for cataract surgery. Keratometry or topography should then be repeated 2 weeks later to ensure the stability of the cornea before these measurements are used for biometry. Therefore, the effect of pterygium excision on intraocular lens IOL power calculation has been examined in our previous study.
The study confirmed that pterygium can cause alteration of IOL power. Variable A denotes the A-constant of the intraocular lens which is dependent on the IOL material and refractive index. Other variables for input include axial length AL and keratometry K.
A larger K reading will result in a lower estimated IOL power and vice versa. Previous studies have documented simultaneous cataract and pterygium operation resulted in reasonable visual outcome without adjustment of IOL power. With the presence of a pterygium, the cornea is flattened and lead to a reduction of K value and over-estimation of calculated IOL power. This randomized controlled trial is designed to compare the refractive outcomes of sequential and simultaneous pterygium and cataract operation.
Pterygium excision should be done with various adjuvant therapies to minimize recurrence. Our previous studies reliably demonstrated limbal conjunctival graft and mitomycin C were effective methods to achieve low pterygium recurrence.
We use limbal conjunctival autograft as the adjuvant therapy in the current study because this method is safer to be performed either alone or in combination with phacoemulsification. We avoid using mitomycin C as the adjuvant therapy in order to minimize the possibility of intraocular toxicity due to seepage.
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Search for terms. Save this study. Warning You have reached the maximum number of saved studies Surgical Treatment of Concurrent Cataract and Primary Pterygium The safety and scientific validity of this study is the responsibility of the study sponsor and investigators.
Figure 4. Distribution of the study lot according to general habits, divided by groups. Figure 5. Discussions As seen in the previous section, UV exposure seems to be an important factor influencing both pterygium and cataract, results also confirmed by similar studies [ 8 , 9 , 10 , 11 , 12 ]. Acknowledgments XXX. References 1. The geospatial relationship of pterygium and senile cataract to ambient solar ultraviolet in tropical Ecuador. Photochem Photobiol Sci.
Clin Ophthalmol. Ultraviolet light and ocular diseases. Int Ophthalmol. Association between ultraviolet radiation exposure dose and cataract in Han people living in China and Taiwan: A cross-sectional study.
The prevalence and determinants of pterygium in rural areas. Journal of Current Ophthalmology. The role of ultraviolet radiation in the pathogenesis of pterygia. Molecular Medicine Reports. High prevalence of nuclear cataract in the population of tropical and subtropical areas. Dev Ophthalmol.
Prevalence of pterygium and cataract in indigenous populations of the Brazilian Amazon rain forest. Open Toxicol J. A review: role of ultraviolet radiation in age-related macular degeneration. Eye Contact Lens. Age related macular degeneration and sun exposure, iris colour, and skin sensitivity to sunlight. Br J Ophthalmol. Is sunlight exposure a risk factor for age-related macular degeneration? A systematic review and meta-analysis.
Role of Matrix Metalloproteinases in Photoaging and Photocarcinogenesis. Matrix metalloproteinases and tissue inhibitors of matrix metalloproteinases in the human lens: Implications for cortical cataract formation. Invest Ophthalmol Vis Sci. Vasudevan S, Abraham A. Austin J Clin Ophthalmol. Expression of matrix metalloproteinases of human lens epithelial cells in the cultured lens capsule bag.
West-Mays J. Expert Rev Ophthalmol. Years of sunlight exposure and cataract: a case-control study in a Mediterranean population. BMC Ophthalmol. Prevalence of lens opacities in Asian Malays. Ophthalmic Epidemiol. UVA light in vivo reaches the nucleus of the guinea pig lens and produces deleterious, oxidative effects. Exp Eye Res. Arch Ophthalmol.
Ultraviolet B exposure and type of lens opacity in ophthalmic patients in Japan. Sci Total Environ. UVB-mediated down-regulation of proteasome in cultured human primary pterygium fibroblasts.
BMC Ophthalmology. Differential expression of matrix metalloproteinases and their tissue inhibitors at the advancing pterygium head. Relationship between pterygium and age-related cataract among rural populations living in two different latitude areas in China. Int J Clin Exp Med.
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