Changes In Corneal Sensitivity Research Articles

Ocular Surface Findings in Hallopeau-Siemens Subtype of Dystrophic Epidermolysis Bullosa

This article describes the clinical features and long-term changes in corneal sensitivity, tear function, and impression cytology findings in a patient with recessive dystrophic epidermolysis bullosa (DEB). The patient underwent best-corrected Landolt visual acuity measurements, slit-lamp examinations, anterior segment photography, Schirmer test with anesthesia, tear film break-up time, corneal fluorescein and Rose-Bengal staining, assessment of corneal sensitivity, and conjunctival impression cytology at the initial and final visits. The patient had a recurrent corneal erosion in the right eye and a painful corneal blister with extensive superficial punctuate keratopathy in the left eye, which remained refractory to treatment with patching, lubricants, and antibiotic ointments for 10 weeks. The corneal disease in both eyes responded swiftly to topical fibronectin, topical nonpreserved tears, vitamin A ointment, and therapeutic soft contact lenses. Maintenance treatment was continued with preservative-free topical tear drops and vitamin A ointment. Corneal disease did not recur in the patient during the follow-up of 29 months. The mean corneal sensitivity and tear film break-up time were decreased initially in both eyes and attained normal values with treatment. Impression cytology revealed squamous metaplasia, loss of cellular cohesion, and total absence of goblet cells before treatment, all of which were observed to be normalized at the final follow-up. The ocular surface disease in DEB was characterized by low corneal sensitivity, disorder of tear quality, decreased cellular cohesion, squamous metaplasia of the conjunctiva, and goblet cell loss. Close follow-up for ocular complications in DEB is essential and a pathophysiology-oriented approach to the epithelial disease may not only provide rapid healing but might prevent recurrences as well.

Effect of laser in situ keratomileusis on tear secretion and corneal sensitivity.

To study changes in corneal sensitivity and Schirmer I scores following laser in situ keratomileusis (LASIK) and the correlation between the two. Twenty-three patients who had LASIK at The Gimbel Eye Center, Toronto, Ontario, Canada, participated in the study. All were asymptomatic for severe dry eyes before surgery. All patients underwent a Schirmer test (without anesthetic), a filament corneal sensitivity test, and slit-lamp microscopy including staining with lissamine green preoperatively and at postoperative time intervals of 3 to 5 days, and 1 and 3 months. No correlation was found between the difference in Schirmer test scores and the difference in corneal sensitivity, at any timepoint. A non-statistically significant trend toward a reduction in Schirmer values immediately after surgery was noted, with a return to slightly lower than baseline levels by 3 months. Corneal sensitivity was significantly decreased immediately after surgery and returned to preoperative levels by 3 months (P<.0001). There was a statistically significant effect of age, gender, and mean spherical equivalent refraction on corneal sensitivity (P<.0001) and a significant effect of age on the time trend (P=.02), but not for Schirmer levels or staining. A significant reduction in corneal sensitivity immediately following surgery occurred, with a return to preoperative levels by 3 months. Schirmer test scores similarly decreased, although without statistical significance, and returned to near preoperative levels after 3 months. A statistically significant correlation between the reduction in tearing and reduction in corneal sensitivity after LASIK was not demonstrated.

Effect of myopic LASIK on human corneal sensitivity

Objective To evaluate the changes in corneal sensitivity after LASIK for the correction of different degrees of myopia. Design Prospective, nonrandomized, comparative self-controlled trial. Participants One hundred two myopic eyes of 58 patients were included in this study. Methods The eyes were divided into four groups: group 1, from −0.75 to −3.75 diopters (D); group 2, from −4.00 to −7.75 D; group 3, from −8.00 to −11.75 D; group 4, from −12.00 to −16.00 D. Corneal sensitivity was measured before and 1, 7, 30, 90, 180, 270, and 365 days after surgery or until full recovery. Main outcome measures The recovery of corneal sensation after LASIK. Results Immediately after surgery, the lenticule was found to be completely anesthetic, and the full recovery varied according to the depth of the ablation. Normal levels of corneal sensitivity, but not full recovery, were found after 90 days in groups 1 and 2 and after 180 days in groups 3 and 4. Full recovery of corneal sensitivity was found after 180 days in groups 1 and 2 and after 270 days in groups 3 and 4. Conclusions After LASIK, corneal sensitivity is decreased at the central and paracentral areas for as long as 9 months. The depth of the ablation seems to be an important factor in the temporary decrease of corneal sensitivity and its recovery.

Sensibilidade corneana e secreção lacrimal após LASIK

OBJETIVO: Avaliar as alterações que ocorrem na sensibilidade corneana e secreção lacrimal após a cirurgia de "laser in situ keratomileusis" (LASIK). MÉTODOS: Foram examinados 38 olhos de 19 pacientes, 9 homens e 10 mulheres submetidos à cirurgia de LASIK para correção de miopia com equivalente esférico médio de -3,79 D (± 1,29 D). A sensibilidade corneana foi medida com o estesiômetro de Cochet-Bonnet, na região central da córnea. A secreção lacrimal foi avaliada pelos testes de Schirmer I, secreção basal, medida do tempo de rotura do filme lacrimal, e sintomatologia apresentada. Os exames foram realizados antes e após 7, 30, 90, 180 e 270 dias da cirurgia ou até que os níveis pré-operatórios fossem atingidos. RESULTADOS: Antes da cirurgia, o valor mediano da sensibilidade tátil corneana foi de 60,0 mm (variando de 50 a 60 mm); o teste de Schirmer I apresentou mediana de 21,5 mm (variando de 10 a 30 mm); o teste de secreção basal obteve mediana de 11,5 mm (variando de 6 a 20 mm); o tempo de rotura do filme lacrimal alcançou mediana de 16,0 segundos (variando de 8 a 22 segundos). Todos os pacientes recuperaram seus valores pré-operatórios de sensibilidade corneana e secreção lacrimal entre 90 e 180 dias após a cirurgia. Durante os 9 meses de seguimento, 5 pacientes (10 olhos) não apresentaram qualquer sintoma relacionado a olho seco. CONCLUSÃO: Após a cirurgia de LASIK a sensibilidade corneana e a secreção lacrimal podem ficar reduzidos por até 6 meses. Neste período, 73,6% dos pacientes apresentaram sintomas de olho seco. Estudos futuros são necessários para avaliar os efeitos destas alterações sobre a fisiologia corneana.

Changes in tear function and the ocular surface after topical olopatadine treatment for allergic conjunctivitis: an open-label study

Background: Olopatadine hydrochloride 0.1% eye drops represent a new class of anti-allergic agent with combined antihistaminic and mast cell—stabilizing properties. Objective: The purpose of this study was to describe alterations in tear function and the ocular surface in patients with allergic conjunctivitis and to analyze the effect of topical olopatadine treatment on corneal sensitivity, tear function, and impression cytology variables. Methods: This was a single-center, 3-visit, prospective, open-label study conducted in patients with allergic conjunctivitis. Patients received 1 drop of topical olopatadine hydrochloride 0.1% BID for 3 weeks. At each visit, patients and healthy control subjects underwent routine ophthalmic examinations and measurements of corneal sensitivity and tear function (Schirmer test of tear quantity, tear film break-up time [BUT], fluorescein staining of the cornea). All control subjects and a subgroup of patients also underwent conjunctival impression cytology for assessment of squamous metaplasia and goblet cell density. The outcomes of interest were changes in corneal sensitivity, tear function, and impression cytology variables after 3 weeks of treatment with olopatadine eye drops, both in patients with allergic conjunctivitis and between patients and controls. Results: At enrollment, the study included 46 eyes of 23 patients (9 men, 14 women; age range, 20–42 years) with allergic conjunctivitis; results were calculated based on the 21 patients who completed the study. The control group consisted of 70 eyes of 35 healthy subjects (13 men, 22 women; age range, 22–39 years). Before treatment, 64.3% of the eyes of patients with allergic conjunctivitis had a fluorescein staining score of >1 point, whereas after treatment, 14.3% had a score of >1 point ( P < 0.001). Patients' mean (±SD) corneal sensitivity improved to 55.0 ± 2.5 mm from the pretreatment value of 42.5 ± 2.5 mm ( P < 0.001). Mean BUT values before and after treatment were 8.1 ± 3.5 and 14.0 ± 7.0 seconds, respectively ( P < 0.001). Before treatment, patients' mean squamous metaplasia grade was 2.5 ± 0.5; at the end of treatment, it had decreased to 1.0 ± 0.5 ( P < 0.001). The mean pretreatment goblet cell density of 545 ± 85 cells/mm 2 improved to 1090 ± 100 cells/mm 2 after treatment ( P < 0.001). Conclusion: In the patient population studied, the disorder of tear function, squamous metaplasia, and loss of ocular surface goblet cells associated with allergic conjunctivitis improved with topical olopatadine treatment.

Change in corneal sensitivityfollowing laser in situ keratomileusis

Purpose: To evaluate the change in corneal sensitivity following laser in situ keratomileusis.(LASIK). Setting: Department of Ophthalmology, Maryknoll Hospital, Pusan, Korea. Methods: The corneal sensitivity in 40 eyes (32 patients) was measured before and1 and 2 weeks and 1, 3, and 6 months after LASIK. Sensitivity measurements were made with an esthesiometer at central, temporal, inferior, nasal, and superior points on the corneal flap. The eyes were grouped by ablation depth: Group 1, corneal ablation depth less than 100 μm; Group 2, corneal ablation depth more than 1,00 μm. Results: Corneal sensitivity did not recover to the preoperative level by 6 months after LASIK. Except at the hinge of the corneal flap, the pattern of sensitivity recovery recovery was similar among the various points. Recovery was more rapid at the hinge than at other areas ( P < .05). There Was ,a trend toward a greater reduction in corneal sensitivity in Group 2, the group with deeper ablations, than in Group 1. Conclusion: The results suggest that lamellar cutting of the cornea during LASIK impairs corn corneal sensitivity and that the depth of the corneal ablation affects the extent of corneal sensitivity loss and recovery.

Corneal Sensitivity Changes in Long-Term Wearing of Hard Polymethylmethacrylate Contact Lenses

The effect on corneal sensitivity of years of wearing hard contact lenses was evaluated in 20 subjects who had worn polymethylmethacrylate (PMMA) lenses for up to 20 years. An age- and sex-matched group of 20 eyes was used as the control group. It was found that corneal sensitivity diminished significantly in wearers of PMMA contact lenses. This reduction of corneal sensitivity was found to be most prominent centrally and was markedly related with the duration of PMMA contact lens use. The loss of corneal sensitivity due to wearing contact lenses increases the risk of a silent infection.

The effect of hard and gas permeable contact lenses on refractive error, corneal curvature, thickness and sensitivity

Hard (PMMA) and hard gas permeable (GPH) contact lens wear was monitored over the initial three month period of wear in a total of 66 subjects. The parameters studied were refractive error, corneal curvature, corneal thickness, and corneal sensitivity. The PMMA lenses appear to produce significant changes in each of these parameters. The GPH lenses appear to induce changes in corneal sensitivity only. However an inspection of the PMMA wearing eyes suggests that approximately half undergo changes similar to the GPH wearing eyes and this points to the notion that some prospective contact lens wearers have little to gain from the wearing of GPH lenses. The only parameter which appears to hold any promise of identifying the most appropriate material to use for an individual patient is corneal sensitivity.

Corneal sensitivity in pregnancy.

Only few studies are available on changes in corneal sensitivity during pregnancy, and most of the earlier work was done with instruments which gave only a rough approximation of the threshold of corneal sensitivity to touch. The new esthesiometer developed by Draeger permits, for the first time, an exact and reproducible determination of the threshold of corneal sensitivity to touch. We studied corneal sensitivity in 86 pregnant women between the 13th and 40th week of gestation. The thresholds were significantly higher in the study as compared to a control group of non-pregnant women. The decrease in corneal sensitivity was not related to duration of gestation, weight gain during pregnancy or mean arterial pressure at the time of examination. Possible mechanisms responsible for changes in corneal sensitivity in pregnancy are discussed.

Effects of timolol on corneal sensitivity and tear production.

A double-masked study was carried out to assess the effect of timolol ophthalmic-solution on corneal sensitivity in seven normal volunteers. No significant change in corneal sensitivity was demonstrated during four weeks of timolol administration. Corneal sensitivity was determined in two age-matched groups, one comprising 27 glaucomatous patients on timolol therapy for at least three months and the other consisting of 24 normal individuals who had never been on any beta-blocking agents. No significant difference in corneal sensitivity was noted between the two groups. The tear production was determined by means of the Schirmer test I in 15 patients with primary open-angle glaucoma or ocular hypertension prior to and during timolol therapy of 13 months duration. No significant change in tear production was noted.

Effect of oxygen deprivation on corneal sensitivity.

The effect on corneal sensitivity of exposing the cornea to reduced partial pressure of atmosphere oxygen for up to 10 h was evaluated. It was found that corneal sensitivity diminished markedly with 2.1% and 3.15% partial oxygen pressure. It is suggested that lower than normal oxygen pressure at the corneal surface is mainly responsible for significant changes in corneal sensitivity.

Corneal response to thick and thin hydrophilic lenses.

Thick and thin hydrophilic lenses with otherwise similar parameters were worn by patients for a period of 6 months. The thicker lenses produced greater changes in corneal sensitivity and thickness during the course of adaptation and wear than did the thinner lenses. Chronic edema levels of 3--4% were noted with the thick lenses. Changes in corneal power for each lens group were not significant. Thin hydrophilic lenses seemed to produce less upset of normal corneal physiology over the course of the 6-month wearing period.

Influence of menstruation on corneal sensitivity.

Corneal sensitivity was measured over a 28 day period in 3 groups of subjects-- females females taking oral contraceptives (OC) and males--to determine variations of the corneal touch threshold of young women during the menstrual cycle. As compared to the rest of the cycle corneal sensitivity was reduced markedly during the premenstruum and abo ut the time of menstruation. Discernible changes in corneal sensitivity were absent among women taking OCs and men. Because these changes were absent among OC users and men it is suggested that these results may be associated with generalized edema induced during the premenstruum.