Mechanism of Corneal Topographic Changes

Oldenburg, J. Brent; Garbus, Jenny; McDonnell, Jan M.; McDonnell, Peter J.

doi:10.1097/00003226-199007000-00004

Cited by 93 publications

(67 citation statements)

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“…Oldenburg et al 6 reported, in their study performed using a keratometer and a corneoscope, that the cornea became more regular following removal of pooling of tears at the pterygium apex. In our study, we observed that pterygium causes serious corneal astigmatism (4.3171.91 D), and this astigmatism reduces (2.1971.55 D) following dried pooling of tears at the pterygium apex.…”

Section: Discussionmentioning

confidence: 99%

“…4,5 Pterygia may lead to visual impairment invading the visual axis or distorting central corneal topography, and induce a focal corneal flattening and severe astigmatism demonstrated by an increasing ovality of corneoscope mires in the meridian of the pterygium. [6][7][8][9][10] The reason for this astigmatism has not been found yet. A possible cause could be local pooling of tears at the pterygium apex.…”

Section: Introductionmentioning

confidence: 99%

“…A possible cause could be local pooling of tears at the pterygium apex. 6 Such pooling may be indicative of the corneal flattening. Another possible cause may be the exertion of traction forces by contractile elements within the pterygium that mechanically distort and flatten the cornea.…”

Section: Introductionmentioning

confidence: 99%

“…An ultrastructural study has revealed that there are no myofibroblast cells within pterygium tissue. 6 In this study, we investigate the effects of fibrovascular traction and the pooling of tears at the pterygium apex on corneal topography using a computerized corneal topography system.…”

Section: Introductionmentioning

confidence: 99%

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Effects of fibrovascular traction and pooling of tears on corneal topographic changes induced by pterygium

Yaşar

Özdemir

Çinal

et al. 2003

Eye

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Aim To investigate the effects of fibrovascular traction and the pooling of tears at the pterygium apex on the corneal topographic changes induced by pterygium. Methods A total of 16 eyes of 14 cases with primary pterygium were included in the study. A computerized corneal topography system was used for corneal topography examinations. Baseline keratographs were taken two times at straight gaze. A repeat corneoscope photograph was immediately obtained in temporal gaze. Then the tears at the pterygium apex were dried with a cellulose sponge, and a new corneoscope photograph was immediately obtained without allowing one to blink. Corneal topographic maps (numeric maps) were divided into 301 fields in 24 meridians. One colour was allocated to each field, representing its mean refractive power for all groups. In all eyes, keratometric astigmatism at the 3 mm central cornea and total mean corneal refractive power were found. Data were compared using pairedsamples two-tailed t-tests.Results Keratometric astigmatism at the 3 mm central cornea was significantly reduced at the temporal gaze (3.1072.34 D, t ¼ 3.40, P ¼ 0.027) and dried eyes (2.1271.01 D, t ¼ 4.74, P ¼ 0.001) according to the first baseline measurement (4.3171.91 D) of the total mean corneal refractive power was found to be 43.4571.28 D (39.29-45.87) at the first baseline measurement. There was no change at the temporal gaze (43.5471.06 D, P40.05). However, the total corneal refractive power was significantly higher in dried eyes (44.2670.93 D, t ¼ 34.92, Po0.001). The steepest region of corneal topography was a superior quadrant, and the flattest area was a nasal quadrant at the baseline. At the temporal gaze, the cornea was significantly flatter in the superior and inferior sides of the pterygium meridian. After dried pooling of tears, topographic abnormalities returned, and the cornea became more uniform and symmetric. Conclusion We conclude that the pooling of tears at the pterygium apex plays an important role, but fibrovascular traction has no effect on the corneal topographical changes induced by pterygium.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of fibrovascular traction and pooling of tears on corneal topographic changes induced by pterygium

Yaşar

Özdemir

Çinal

et al. 2003

Eye

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“…Some authors [5,6] have considered the main role of pooling of tears and formation of tear meniscus between the corneal apex and the elevated head of pterygium, but have excluded any role of fibrovascular traction. Other investigators like Budack et al [7] hypothesized that the flattening of the cornea is due to the mechanical traction exerted by the lesion.…”

Section: Resultsmentioning

confidence: 99%

Comparative study of astigmatic changes following pterygium excision with conjunctival autograft transplantation

Zheleva

Voynov

2018

Biotechnology & Biotechnological Equipment

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This prospective clinical study compared the corneal astigmatism before and after pterygium excision surgery with conjunctival autograft transplantation. The study included 37 eyes of 37 patients diagnosed with pterygium. All participants underwent pterygium excision with conjunctival autograft transplantation and were examined preoperatively and on the first and third month post-intervention. Comprehensive ophthalmic examination was done and measurements included: pterygium size, uncorrected and best corrected visual acuity and corneal astigmatism. Preoperative and postoperative values were compared using the nonparametric Wilcoxon signedranks test. The mean pterygium horizontal length was 2.18 mm (range 1-4 mm). A statistically significant correlation was observed between the pterygium length and preoperative astigmatism. The mean corneal astigmatism preoperatively was 1.26 § 1.18 D and decreased to 0.84 § 0.73 D three months after the intervention (p < 0.001). The mean UCVA (uncorrected visual acuity) preoperatively was 0.75, improving to 0.77; the mean BCVA (best corrected visual acuity) before surgery was 0.86, improving to 0.87 after the procedure. These results demonstrated that the amount of induced astigmatism increased in proportion to the size of the pterygium increase. The corneal astigmatism tended to decrease significantly following pterygium excision with conjunctival autograft transplantation.

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Fibrin glue versus sutures for conjunctival autografting in primary pterygium surgery

Romano¹,

Cruciani²,

Conti³

et al. 2014

Cochrane Database of Systematic Reviews

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Mechanism of Corneal Topographic Changes

Cited by 93 publications

References 0 publications

Effects of fibrovascular traction and pooling of tears on corneal topographic changes induced by pterygium

Effects of fibrovascular traction and pooling of tears on corneal topographic changes induced by pterygium

Comparative study of astigmatic changes following pterygium excision with conjunctival autograft transplantation

Fibrin glue versus sutures for conjunctival autografting in primary pterygium surgery

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