|Year : 2018 | Volume
| Issue : 3 | Page : 95-98
Detecting ocular surface changes associated with soft contact lens wear using conjunctival impression cytology
Swathi Nagarajan1, MP Narmada2, N Kavitha3
1 Department of Ophthalmology, Mahatma Gandhi Medical College and Research Institute, Sri Balaji Vidyapeeth University, Puducherry, Tamil Nadu, India
2 Department of Pharmacy Practice, Nehru College of Pharmacy, Thrissur, Kerala, India
3 Department of Pharmacy, Ultra College of Pharmacy, Madurai, Tamil Nadu, India
|Date of Web Publication||23-Oct-2018|
74, 4th Cross, Thanthai Periyar Nagar, Ellaipillaichavady, Puducherry - 605 005
Source of Support: None, Conflict of Interest: None
Context: Contact lenses (CLs) offer middle ground for those not wishing to wear glasses nor undergo refractive surgeries. These lenses may cause ocular surface changes which cause discomfort on using CLs. Aims: This study aims to evaluate conjunctival cytological changes induced by regular CL use among college students and to determine correlation, if any, between the cytological alteration and symptoms and pattern of CL wear. Settings and Design: This was cross-sectional, observational study. Materials and Methods: Thirty-three students wearing CL and an equal number of age-matched controls were evaluated. Data regarding pattern of CL use were collected. Conjunctival impression cytology (CIC) was performed, appropriately stained, and assessed for cytological changes using the Nelson grading system. Statistical Analysis Used: Odds ratio and Chi-square test to determine the prevalence of conjunctival changes in CL users and those with discomfort. Logistic regression analysis is to determine statistically significant association with alteration in conjunctival cytology. P < 0.05 was considered to be statistically significant. Results: Conjunctival cytological changes were seen exclusively in CL users. The duration of use produced a statistically significant effect on conjunctival cytological changes (P < 0.001). Abnormal conjunctival cytological changes were seen in a majority of symptomatic users (odds ratio: 16.9; P < 0.001). Conclusion: The prevalence of conjunctival cytological alterations is more in symptomatic CL wearers and increases with duration of CL use.
Keywords: Conjunctiva, contact lens, impression cytology
|How to cite this article:|
Nagarajan S, Narmada M P, Kavitha N. Detecting ocular surface changes associated with soft contact lens wear using conjunctival impression cytology. J Clin Ophthalmol Res 2018;6:95-8
|How to cite this URL:|
Nagarajan S, Narmada M P, Kavitha N. Detecting ocular surface changes associated with soft contact lens wear using conjunctival impression cytology. J Clin Ophthalmol Res [serial online] 2018 [cited 2019 May 22];6:95-8. Available from: http://www.jcor.in/text.asp?2018/6/3/95/243841
Contact lenses (CLs) are thin optical corrective lenses worn on the eye, resting on the surface of the cornea. Used by approximately 140 million people worldwide, it offers a middle ground for those who neither wish to use spectacles nor undergo refractive surgeries. Of the different types of CLs available, soft hydrophilic CLs have become quite popular owing to their comfort and ease of adaptation to the ocular surface. However, they are prone to deposits and are difficult to keep clean. CL wear is also known to lead to ocular surface changes and is the primary cause of CL discomfort (CLD).
The purpose of this study was to determine conjunctival surface epithelial changes, if any, in CL users using the conjunctival impression cytology (CIC) technique and find any correlation between cytological changes and pattern and symptoms related to CL wear.
| Materials and Methods|| |
The study was carried out in a residential college in rural Tamil Nadu. Thirty-three individuals between 17–25 years of age and wearing CL in both eyes and 33 healthy non-CL-wearing individuals were recruited. The protocol was approved by Institute Ethics Committee, and a consent form was signed in all cases. Those with a history of ocular trauma, previous ophthalmic surgical procedures and with evidence of ocular surface disorder on slit lamp examination were excluded from this study. Tear break up time and examination of Meibomian gland More Details orifices and meibomian secretion by digital expression were used to assess for ocular surface disorder. All individuals were asked to fill a questionnaire regarding their pattern of CL use and symptoms of irritation, redness, or blurring of vision during CL wear.
Ultipor N66 filter paper with a 0.02 μm pore diameter was cut into approximately 4 mm × 5 mm size strips. After installation of a topical anesthetic (0.5% proparacaine), the filter paper was applied to the superior bulbar conjunctiva, 2–3 mm away from the limbus. After holding for 3–4 seconds, the paper was removed by a peeling motion with a forceps. The filter paper was fixed with 95% ethyl alcohol for 10 min and then stained using Papanicolaou staining kit. All slides were evaluated by a single pathologist who was masked to the origin of the slide. The slides were observed under 40X magnification and graded according to Nelson's criteria [Table 1]. Furthermore, the presence of snake-like chromatin, if any, was noted.
The results were examined with Microsoft Excel Version (2007) for frequency distribution and computed in percentages. Data were analyzed using MedCalc for Windows, version 13.3.1 (MedCalc Software, Ostend, Belgium). Odds Ratio and Chi-Square test were done to compare the prevalence of conjunctival epithelial changes in CL users and those with CLD. Logistic regression analysis was performed to determine the statistically significant association, if any, for changes in conjunctival epithelial morphology. P < 0.05 was considered as statistically significant.
| Results|| |
The mean age of the CL users was 22.4 years (17–25 years) and that of non-CL–wearing individuals was 20.9 years (17–24 years). There were 31 females and 2 males in both groups. The mean duration of CL use was 29.9 ± 18.7 months (range 1–84 months). The mean age of the present pair of CL was 7.4 ± 6.1 months (range 1–19.6 months). All CL users claimed to follow the manufacturer's instructions for use and storage of the lenses. CLD was recorded in 33% of CL users (n = 11). The pattern of CL use among the participants is provided in [Table 2].
All 66 eyes in the control group showed normal conjunctival morphology while 22 (33%) eyes of CL users showed grade 1 changes (odds ratio: 67.2; P < 0.001) [Figure 1] and [Figure 2]. No snake-like chromatin was noted. Changes in conjunctival morphology were observed in only 6 (14%) eyes of asymptomatic patients as compared to 16 (73%) eyes of the 11 symptomatic patients (odds ratio: 16.9; P < 0.001). Chi-square test showed a significant relationship between CLD and conjunctival morphological alterations (P< 0.001).
|Figure 1: Photomicrograph of Grade 0 CIC changes showing sheets of small round epithelial cells with nucleo-cytoplasmic ratio of 1:2 (PAP, ×400)|
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|Figure 2: Photomicrograph of Grade 1 CIC changes showing larger polygonal epithelial cells with nucleo-cytoplasmic ratio of 1:3 (PAP, ×400)|
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Logistic regression analysis on conjunctival cytology showed a statistically significant effect with a duration of CL use (P< 0.001), presence of CLD (P< 0.001), and the use of indigenous CL cleaning solutions (P< 0.001).
| Discussion|| |
The human tear film is a tri-layer structure comprising of an outer lipid layer, a middle aqueous layer and an inner mucous layer. The inner mucin layer is a dynamic complex of mucin secreted by the conjunctival goblet cells, the lacrimal gland, and trans-membrane mucin at the microplicae of the stratified epithelium of conjunctiva and cornea. The tear film is essential in maintaining corneal health by supplying nutrients and flushing away of metabolic by-products. It also provides protection against shear forces generated during blinking and eye movements.
There must be a harmonious “Lens-Tear-Cornea” interaction for a successful CL wear. When a CL is placed on the eye, the lens divides the tear film into two layers, the outermost layer that overlies the lens (prelens tear film) and the layer between the back surface of the lens and the cornea (postlens tear film). Tear exchange involves fluid circulation between the pre- and post-tear film. This is essential to minimize the stagnation of metabolic by-products between the lens and cornea, thereby protecting the epithelial barrier function and delaying the onset of adverse events.
Mechanical irritation associated with CL induces a squamous metaplasia of the conjunctival and corneal epithelium and alters the expression and glycosylation of transmembrane mucin. Further, CLs also induce changes in the tear film by immobilizing the lipoidal components and exposing them to oxidation. This results in thinning of the prelens tear film with increased tear evaporation rate and reduced tear break up time. All these contribute to changes in the conjunctival epithelium similar to those observed in ocular surface disorders and dry eye.
Some workers have demonstrated that the prevalence and severity of conjunctival squamous metaplasia and goblet cell loss correlated with an increasing duration of lens wear and CLD., In this study, 15 participants recorded CL use of more than 3 years with cytological changes seen in 11 individuals. However, a relationship between duration of CL wear and severity of cytological alterations could not be demonstrated as CIC findings were limited to Grade 1 in all cases. In a recent literature review of 24 CIC studies, it was seen that there was no clearly definable relationship between the duration of CL wear and the extent of the development of squamous metaplasia or decrease in goblet cell density. Furthermore, conjunctival changes were observed even in asymptomatic CL users. The effects of different types of CLs on the conjunctival epithelium is not clear as some studies indicate no difference in cytological changes with different lens materials while others showed increased cytological alterations with soft CL use., Larger diameter, greater mobility, increased surface area of contact with conjunctiva and predisposition to deposits may account for this. Nevertheless, conventional soft CLs continue to be extremely popular due to reasonable cost and ease of usage.
Introduced first by Egbert et al., CIC is a popular minimally invasive and painless procedure to examine the superficial layers of the conjunctival epithelium. It can help in identifying not only those at risk of developing symptoms but also helps in assessing the severity of cytological alterations in persons with CLD., CIC can be considered in an OPD setting for CL users so that patients with conjunctival changes can be identified and followed up regularly. Disadvantages of CIC are some loss of morphological details and poor cell yield in case of keratinizing lesions.
The hot and arid climate of interior Tamil Nadu could by itself predispose symptoms of dry eye. The wearing of a CL in this harsh environment requires special attention to proper use. Ophthalmologists and optometrists can educate users about the possible deleterious effects of prolonged CL wear and encourage regular reviews even if asymptomatic to detect any corneal or conjunctival changes.
| Conclusion|| |
The prevalence of conjunctival cytological alterations is more in symptomatic CL wearers and increases with duration of CL use.
The authors would like to thank the students and management of Vivekanandha Group of Institutions, Tiruchengode, Tamil Nadu, for their cooperation during this study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2]