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. Author manuscript; available in PMC: 2022 Sep 1.
Published in final edited form as: Eye Contact Lens. 2021 Sep 1;47(9):515–519. doi: 10.1097/ICL.0000000000000802

Dry eye symptoms in individuals with keratoconus wearing contact lenses

Ellen Shorter 1, Jennifer Harthan 2, Amy Nau 3, Jennifer Fogt 4, Dingcai Cao 5, Muriel Schornack 6, Cherie Nau 7
PMCID: PMC8385958  NIHMSID: NIHMS1693197  PMID: 34424225

Abstract

Objectives:

To assess dry eye symptoms associated with different contact lens modalities in patients with keratoconus using a dry eye questionnaire.

Methods:

An online survey was distributed by the National Keratoconus Foundation which asked participants to report demographic characteristics, current optical correction, age at the time of diagnosis of keratoconus, and contact lens history. The 12 item Ocular Surface Disease Index (OSDI) questionnaire was also completed. Data from participants wearing the same contact lens modality bilaterally were analyzed.

Results:

The survey was completed by 197 individuals wearing the same contact lens modality bilaterally. The average age of participants at the time of the survey was 47.2 ± 14.8 years (range: 15-87) and the average age at which keratoconus was diagnosed was 26.1 ± 9.9 years (range: 8-55 years). The mean overall OSDI score of all participants was 40.2 ± 22.8 (range: 0-100). There was no difference in the mean OSDI scores based on current contact lens modality type (F=1.79; n=187; P=0.13).

Based on OSDI score of 33 or higher, 90% of participants reported symptoms indicative of dry eye disease. Scleral lens wearers reported less discomfort on the individual items related to windy and low humidity conditions.

Conclusions:

Individuals with keratoconus, irrespective of contact lens modality, report a high incidence of dry eye symptoms.

Keywords: contact lens, dry eye syndrome, keratoconus, OSDI, ocular surface disease

Keratoconus impairs visual acuity due to corneal irregularity; patients with moderate or severe disease frequently require therapeutic contact lenses to achieve functional vision. The type of optical correction prescribed for a patient is often determined by both disease severity and patient preference. Patients with mild keratoconus may achieve acceptable vision with spectacles alone or standard soft contact lenses. Those with more advanced disease and high amounts of irregular corneal astigmatism often obtain improved visual acuity with customized corneal gas permeable (GP), hybrid, or scleral lenses. Historically, corneal GP lenses have been the preferred refractive correction for keratoconus.1,2,3

Successful contact lens wear may be complicated by dry eye symptoms. Patients with keratoconus have been shown to have lower tear volumes and more severe dry eye symptoms compared to age matched healthy controls.4 Many previous studies have assessed dry eye symptoms utilizing the OSDI questionnaire in both contact lens wearers and individuals with keratoconus.5-14 Given the plethora of contact lens choices, practitioners should consider not only which lens type will provide the best optical correction for a particular patient, but also the impact of lens choice on patient comfort and overall wearing experience. While corneal irregularity is the most common indication for scleral lens wear, scleral lenses are also used to manage severe ocular surface disease.15-17 In some practices, scleral lenses may be prescribed to help manage discomfort associated with dry eye in patients with keratoconus. Reductions in dry eye symptoms have been reported in patients wearing scleral lenses after a period of one year.18 In addition to providing optical correction for patients with keratoconus, scleral lenses may also provide some level of relief of dry eye symptoms in this population.19-23 It would therefore be reasonable to hypothesize that individuals with keratoconus wearing scleral lenses may have less dry eye symptoms compared to individuals using other contact lens modalities. This study utilized a validated questionnaire to evaluate symptoms of dry eye in patients with keratoconus who were wearing different contact lens modalities.

Methods

A survey was developed by the Scleral Lenses in Current Ophthalmic Practice Evaluation (SCOPE) study group to query symptoms of dry eye in persons with keratoconus. The survey queried participant demographics, mode of correction, as well as dry eye symptoms and visual function utilizing the Ocular Surface Disease Index (OSDI) questionnaire. Study data were collected and managed using REDCap (Research Electronic Data Capture), a secure, web-based software platform designed to support data capture for research studies, which was hosted at Mayo Clinic, Rochester, MN, USA.24,25 Links to the survey were distributed by the National Keratoconus Foundation via their electronic newsletter and website between October 2016 and March 2017. The study was reviewed and approved by the Mayo Clinic Institutional Review Board.

Individuals with a self-reported history of keratoconus were invited to complete the survey; participants were not required to respond to each item. Participants were asked to report their sex, country of residence, race, current optical correction modality, current age, age at the time of diagnosis of keratoconus, and history of initial and all contact lens treatments for keratoconus.

Participants also completed the 12 item OSDI questionnaire for assessing dry eye symptoms and vision-related function.26 This validated questionnaire rates dry eye symptoms experienced during the week preceding completion of the survey, and includes sections on ocular symptoms, difficulties performing daily tasks, and environmental factors on a scale of 0 to 4 (0=none of the time, 1=a little of the time, 2=some of the time, 3=most of the time, 4=all of the time). OSDI scores correlating to ocular surface disease are categorized as normal (0-12 points), mild (13-22 points), moderate (23-32 points), or severe (33-100 points).26 The OSDI questionnaire correlates well with other established questionnaires including the NEI VFQ-25 and the McMonnies questionnaire.26 Participants were not specifically instructed to complete the survey with contact lens wear included. In addition to comparing overall OSDI scores, individual items within the survey were also analyzed for differences between wearers of various lens modalities.

Data from participants wearing the same contact lens modality bilaterally (soft, hybrid, piggyback, corneal GP, or scleral) were included in this analysis as survey items did not query issues for the right and left eyes individually. Data were summarized with descriptive statistics including mean, standard deviation, and range. The one-way analysis of variance (ANOVA) was used to determine if there were any statistical differences between the means of the continuous variables of the five groups of contact lens wearers and Tukey’s Post-hoc test was then used to compare group means. A two factor analysis of variance of this population was also completed for age and gender to assess OSDI results.

Results

Participants

There were 197 of 422 total respondents that met the criteria for wearing the same contact lens modality bilaterally (80 male, 116 female, 1 unknown sex). The majority of participants resided in the United States (77%, n=152) with the rest from 22 other countries. Participants were primarily white (81%, 159) followed by African American/Black (11%, 21), other (4%, 8), Asian (4%, 7) and less than 1%, (1) American Indian or Alaska Native (n=197).

Distribution of participants by lens type is as follows: 11 individuals (5.6%) wearing soft lenses, 12 (6.1%) wearing piggyback systems, 23 (11.7%) wearing hybrid lenses, 75 (38.6%) wearing corneal GP lenses, and 76 (38.6%) wearing scleral lenses. The average age of participants, at the time of the survey, was 47.2 ± 14.8 years (range: 15-87, n=193) with no differences in age between participants (F=1.79; P=.13, Table 1). The average age at diagnosis of keratoconus was 26.1 ± 9.9 years (range: 8-55, n=195) with soft and scleral lens wearers being older at the time of diagnosis of keratoconus compared to piggyback lens wearers (F=3.9, n=195, P=.005, Table 1).

Table 1:

Participant demographics reported by current lens modality group and combined groups.

Mean ±
Standard
Deviation
Range		 Soft Hybrid Piggyback Corneal
Gas
Permeable		 Scleral All Groups
Age at time of survey completion 45.5 ± 10.3 R: 31-58
n=11		 44.2 ± 13.9 R: 21-70
n=23		 47.4 ± 12 R: 34-72
n=11		 51.9 ± 13.8 R: 21-78
n=73		 48.4 ± 13.9 R: 15-82
n=75		 47.2 ± 14.8 R: 15-87
n=193 P=.13
Age at time of diagnosis 32.2 ± 10.5 R: 20-54
n=11		 24.5 ± 8.0 R: 10-40
n=23		 19.8 ± 5.2 R: 15-31
n=12		 24.6 ± 8.5 R: 8-54
n=74		 28.1 ± 11.3 R: 12-55
n=76		 26.1 ± 9.9 R: 8-55
n=195 P=.005
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Ocular Surface Disease Index Scores

Ninety percent (90%) of participants’ OSDI scores supported the diagnosis of dry eye disease of varying severity (13.9% with mild disease, 16.6% with moderate disease, 59.9% with severe disease; Table 2). There was no difference in the mean OSDI score based on current contact lens modality type (F=1.79; n=187; P=0.13). Although differences were not significant, mean OSDI score was lowest in the scleral lens group (35.2± 20.9, R: 2.1- 93.8) and highest in the hybrid lens group (45.7± 25.2, R: 4.2-100). The mean overall OSDI score of all participants (n=187) was 40.2 ± 22.8 (R: 0-100). There was no difference in mean OSDI score based on age or gender (P>0.05).

Table 2.

OSDI score by contact lens modality and combined OSDI score.

Soft
n=10		 Hybrid
n=22		 Piggyback
n=11		 Corneal Gas Permeable
n=71		 Scleral
n=73		 All Groups
n=187
Number of Participants/%
No Dry Eye (score 0-12) 1
10%		 1
4.5%		 1
9.1%		 5
7%		 10
13.7%		 18
9.6%
Mild Dry Eye (score 13-22) 2
20%		 3
13.6%		 4
36.4%		 6
8.5%		 11
15.1%		 26
13.9%
Moderate Dry Eye (score 23-32) 1
10%		 3
13.6%		 1
9.1%		 15
21.1%		 11
15.1%		 31
16.6%
Severe Dry Eye (score 33-100) 6
60%		 15
68.2%		 5
45.5%		 45
63.4%		 41
56.2%		 112
59.9%
Total OSDI Score 42.0 ± 27.0 R: 7.5-87.5 45.7 ± 25.2 R: 4.2-100 36.2 ± 22.8 R: 11.4-68.2 44.0 ± 23.0 R: 0-100 35.2 ± 20.9 R: 2.1- 93.8 40.2 ± 22.8 R: 0-100
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Table 2 displays OSDI score by contact lens modality and combined OSDI score. The responses to each item of the OSDI for each contact lens modality are summarized in Table 3. There were differences between mean scores for three individual OSDI items. OSDI item 2 asks about symptoms of ocular grittiness. Scleral lens wearers had lower scores (1.0 ± 1.1) than hybrid lens wearers (1.7 ± 1.2) (F=2.49; n= 284; P=.05; Table 3). There were no differences between mean scores of the other lens modality groups for OSDI item 2. There were no differences between contact lens modality groups in the second section of the OSDI questionnaire (items 6-9), which assesses difficulties performing visual tasks.

Table 3:

Responses to each item of the OSDI for each contact lens modality summarized.

Soft
n=10		 Hybrid
n=22		 Piggyback
n=11		 Corneal
Gas
Permeable
n=75		 Scleral
n=73		 All Groups
n=191
Ocular symptoms
Light Sensitivity Item 1 1.7 ± 1.6 R: 0-4 2.2 ± 1.4 R: 0-4 1.8 ± 1.4 R 0-4 2.2 ± 1.5 R: 0-4 1.7 ± 1.3 R: 0-4 2.0 ± 1.4 P=.3
Gritty feeling* Item 2 1.5 ± 1.3 R: 0-3 1.7 ± 1.2 R: 0-4 1.2 ± 0.7 R: 0-3 1.5 ± 1.2 R: 0-4 1.0 ± 1.1 R: 0-4 1.3 ± 1.2 P=.05
Sore Eyes Item 3 1.3 ± 1.2 R:0-3 1.5 ± 1.1 R: 0-4 1.5 ± 1.2 R: 0-4 1.4 ± 1.3 R: 0-4 1.1 ± 1.0 R: 0-4 1.3 ± 1.2 P=.4
Blurred Vision Item 4 1.8 ± 1.2 R: 0-4 1.7 ± 1.2 R: 0-4 1.3 ± 1.0 R: 0-3 1.5 ± 1.3 R: 0-4 1.4 ± 1.3 R: 0-4 1.5 ± 1.2 P=.7
Poor Vision Item 5 1.9 ± 1.4 R: 0-4 1.6 ± 1.4 R: 0-4 1.2 ± 1.3 R: 0-4 1.7 ± 1.3 R: 0-4 1.5 ± 1.3 R: 0-4 1.6 ± 1.3 P=.7
Difficulty performing tasks
Reading Item 6 1.2 ± 1.2 R: 0-4 1.8 ± 1.4 R: 0-4 1.5 ± 1.3 R: 0-4 1.6 ± 1.2 R: 0-4 1.4 ± 1.2 R: 0-4 1.5 ± 1.2 P=.7
Driving at Night Item 7 1.7 ± 1.5 R: 0-4 1.7 ± 1.3 R 0-4 2.1 ± 1.2 R: 0-4 2.4 ± 1.5 R: 0-4 2.2 ± 1.5 R: 0-4 2.2 ± 1.5 P=.4
Computer Work Item 8 1.2 ± 1.4 R: 0-4 1.4 ± 1.3 R: 0-4 1.1 ± 1.1 R: 0-3 1.4 ± 1.2 R: 0-4 1.3 ± 1.1 R: 0-4 1.3 ± 1.2 P=.9
Watching TV Item 9 1.7 ± 1.4 R: 0-4 1.4 ± 1.0 R: 0-4 1.1 ± 0.8 R: 0-2 1.3 ± 1.2 R: 0-4 1.1 ± 1.1 R: 0-4 1.3 ± 1.1 P=.6
Conditions that may increase discomfort
Wind‡ Item 10 2.1 ± 1.2 R: 0-4 2.5 ± 1.4† R: 0-4 1.5 ± 1.2 R: 0-4 2.5 ± 1.4₤ R: 0-4 1.4 ± 1.4 R: 0-4 2.0 ± 1.5 P=.0001
Low Humidity¥ Item 11 2.3 ± 1.3 R: 0-4 2.7 ± 1.4₸R: 0-4 2.0 ± 2.0 R: 0-4 2.2 ± 1.5₣ R: 0-4 1.5 ± 1.4 R: 0-4 2.0 ± 1.5 P=.01
Air Conditioning Item 12 2.3 ± 1.6 R: 0-4 1.7 ± 1.4 R:0-4 1.6 ± 1.5 R: 0-4 1.6 ± 1.4 R: 0-4 1.2 ± 1.3 R: 0-4 1.5 ± 1.4 P=.3
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There were differences between participants wearing various contact lens modalities in two individual items of the third section of the OSDI questionnaire. Item 10 of the OSDI questionnaire queries ocular discomfort in windy conditions. Scleral lens wearers (1.4 ± 0.2) had lower mean scores compared to hybrid lens (2.5 ± 0.3) and corneal GP lens wearers (2.5 ± 0.2; F=6.34; n= 178; P=.0001; Table 3). Item 11 of the questionnaire asks about ocular discomfort in areas of low humidity. Scleral lens wearers (1.5 ± 0.2) had lower mean scores compared to both hybrid lens (2.7 ± 0.3) and corneal GP lens wearers (2.2 ± 0.2; F= 3.26, n=168; P=.01; Table 3). No other single item of the OSDI had significant differences between contact lens modality.

Discussion

In this study, 90% of individuals with keratoconus reported dry eye symptoms. The mean OSDI score overall was 40.2, indicating severe dry eye symptoms in this population, irrespective of lens modality. Indeed, 60% of all participants had OSDI scores that were in the severe dry eye category. This is in agreement with previous studies reporting higher OSDI scores in individuals with keratoconus (44.9 ± 8.7) compared to age matched controls (17.8 ± 6.5) and higher incidence of meibomian gland dysfunction4,27. An additional study by Carracedo et al. also showed patients with keratoconus who use corneal GP lenses had more severe dry eye symptoms and signs, including lower Schirmer test scores, lower tear break up time and higher concentrations of Ap4A and Ap5A than healthy controls28. It is also possible that inadequate or poorly fit lenses could contribute to discomfort which could be misinterpreted as dry eye symptoms and therefore result in higher OSDI scores.

Because scleral lenses are a well-established therapeutic intervention for the management of ocular surface disease29, participants wearing scleral lenses could have been expected to have lower OSDI scores than those wearing other lens modalities. A previous study comparing tear film quality and OSDI in patients with keratoconus before and after one month of scleral lens wear reported a reduction in corneal staining and OSDI scores from 30.3 to 19.212. A previous comparison of overall optical satisfaction in patients with keratoconus revealed that scleral lens wearers may have greater levels of satisfaction with their vision and lens comfort than patients who wear corneal GP lenses30. As scleral lenses have been shown to improve visual acuity, improve comfort, and improve ocular surface health in patients with dry eye disease, it could be hypothesized that higher levels of satisfaction in scleral lens wearers compared to corneal GP lens wears could be due to the therapeutic effects of scleral lenses on ocular surface disease17,21,31. Some practitioners may consider scleral lenses only when other more affordable modalities have failed. Surprisingly, mean overall OSDI scores of 56% of scleral lens wearers were in the severe dry eye category in this study suggesting scleral lens wear does not necessarily provide symptomatic improvement in dry eye compared to other lens modalities.

Analysis of individual OSDI items 10 and 11 suggests scleral lenses may be associated with fewer dry eye symptoms under challenging conditions (windy and low humidity environments) compared to hybrid and corneal GP lenses. Hence, it is possible that scleral lens wear may convey some benefit for patients with keratoconus who experience dry eye symptoms. Additionally, scleral lens wearers reported less issues with a gritty feeling in their eyes. However, additional prospective studies are needed as the OSDI questionnaire has been validated as a complete survey rather than as separate components and not specifically in patients with keratoconus.

Conclusions that can be drawn from this study are limited by some factors common to all survey research (potential selection bias, incomplete survey responses) and by other factors unique to this study. Medical records were not reviewed and participants self-reported a diagnosis of keratoconus. No information on visual acuity, anterior segment examination findings, topographical analysis or stage of disease was available. Clinical background information was also unavailable. Neither details on patient response to prior treatments are known nor providers’ rationale for prescribing the current mode of correction could be ascertained. OSDI scores were collected at a single point in time, so analysis of the effects of various forms of therapeutic intervention or contact lens modality on OSDI scores for a particular individual was not possible. Additionally, OSDI scores prior to fitting with current lens modality are not available, leaving questions as to whether improvement in symptoms of dry eye was actually achieved by refitting into a different modality, even though the current mean OSDI score is high. Nevertheless, this study did provide an opportunity for patients with keratoconus to offer an assessment of the impact of dry eye disease on their overall visual and ocular experience. This study did not compare contact lens wearers with and without keratoconus. It is possible individuals with keratoconus suffer from more atopic disease and allergy which could contribute to more dry eye symptoms. The ability for participants to provide this information anonymously (outside of the confines of an in-person eye examination) may have reduced the potential bias of either over- or under-reporting symptoms in the presence of an eye care provider.

Individuals with keratoconus commonly struggle with both visual challenges and dry eye symptoms. Interestingly, there were no differences in difficulty performing visual tasks including reading, driving at night, computer work and watching tv based on mode of correction. Although one might expect that scleral lenses could provide symptomatic relief from dry eye disease in patients with keratoconus, this study found that scleral lens wearers experience severe dry eye symptoms. However, scleral lenses may provide better comfort in challenging environments compared to other contact lens modalities. Data presented here demonstrate that symptoms of dry eye disease, often severe, are present in the majority of persons with keratoconus using contact lenses bilaterally. Use of validated dry eye surveys at all clinical visits represents an opportunity to efficiently query patients about their symptoms and to prompt further investigation when discomfort is present.

Acknowledgments

Support: This work was supported by the National Institutes of Health and National Eye Institute Core Grant [EY01792], an unrestricted grant to the Department of Ophthalmology and Visual Sciences from Research to Prevent Blindness and the Mayo Clinic Research Computing Facility grant support UL1TR002377.

Portions of this data were presented as research at: Association for Vision Research in Ophthalmology, Honolulu, HI, May 2018 (Experience of keratoconus patients wearing RGP or scleral lenses: A SCOPE Study), Global Specialty Lens Symposium, Las Vegas, NV January 2018 (Scleral Lens Experience in Patients with Keratoconus (SCOPE Study) and American Academy of Optometry, Chicago, October 2017 (Patient-reported experience with keratoconus.)

Contributor Information

Ellen Shorter, University of Illinois at Chicago Department of Ophthalmology and Visual Sciences, 1855 W Taylor Street, Chicago, IL, 60612 USA.

Jennifer Harthan, Illinois College of Optometry, 3241 S. Michigan Ave, Chicago, IL 60616 USA.

Amy Nau, Korb & Associates, 400 Commonwealth Ave Suite #2, Boston, MA 02215 USA.

Jennifer Fogt, Ohio State University College of Optometry, 338 West 10th Ave Room A258 Starling Hall, Columbus, OH 43210 USA.

Dingcai Cao, University of Illinois at Chicago Department of Ophthalmology and Visual Sciences, 1905 W Taylor Street, Chicago, IL 60612 USA.

Muriel Schornack, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 USA.

Cherie Nau, Mayo Clinic, 200 1st St SW, Rochester, MN 55905 USA.

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