Changes in quality of life after laser in situ keratomileusis for myopia

INTRODUCTION

With the global burden of refractive error being 2.2 billion, it has become the most common cause of treatable blindness and visual impairment in the world. Uncorrected refractive error causes visual impairment in approximately 88.4 million people.^[1]

The prevalence of at least 0.50 D of spherical equivalent ametropia in India is estimated to be about 53%.^[2] Uncorrected refractive error can adversely affect the quality of life (QoL) of patients, leading to socioeconomic segregation due to subpar educational and employment opportunities.^[3] While the use of spectacles and contact lenses is usually the first choice for correcting refractive error in myopic patients, in recent years, refractive surgery is gaining popularity even among people who use contact lenses. Refractive surgeries may be cornea-based or lens-based. Cornea-based procedures encompass surface-based techniques such as photorefractive keratectomy (PRK), laser-subepithelial keratomileusis and epi-laser in situ keratomileusis (LASIK) or lamellar techniques like LASIK.^[4]

While procedures of LASIK and PRK have been modified, new modalities like small incision lenticule extraction (SMILE) have been recognised. Still, LASIK continues to be the most commonly performed refractive surgery.^[5] These refractive surgeries are easy to perform, hassle-free, completed quickly and have a short post-operative recovery period.^[6] Results of refractive surgery can be documented by clinical parameters such as uncorrected visual acuity (UCVA) before and after surgery. Although these measurements provide vital information, they cannot evaluate the role played by medical interventions in the QoL of these patients. Thus, to reveal patient’s concerns, in addition to evaluating refractive surgery results by clinical measurements, their QoL should also be taken into consideration.

The study of QoL using questionnaires can aid in understanding how the socio-personal life of myopic patients is affected by their refractive error. In addition, the effect of surgical methods in treating them can be assessed. To evaluate this efficacy in our patients, we aimed to measure the QoL outcomes in patients having myopia and myopic astigmatism after undergoing refractive surgery with the help of the quality of life impact of refractive correction (QIRC) questionnaire.^[7]

MATERIALS AND METHODS

Sixty-one patients undergoing LASIK for myopia and myopic astigmatism in the operation theatre complex during a period of 2 years from 2016-2018, aiming for full correction, were enrolled in this study after taking informed consent. The protocol was reviewed and approved by the institutional review board.

Primary outcomes were pre- and post-surgery QoL scores as obtained from the QIRC questionnaire, which were then categorised into glare-related, vision-related, psychosocial and financial categories. These were further cross-tabulated with refractive error categories high (>−6.00D), moderate (−3.00D–−6.00D) and low (<−3.00D). Secondary outcomes included pre- and postoperative visual acuity and postoperative refractive error.

Sample size was decided based on the outcomes of the previous studies: Percentage of improved mean QIRC score after surgery = 32.9%, absolute precision (%) = 12%, derived confidence level (1-α) = 95. Thus, the minimum sample size required for the study was estimated to be 60. We enrolled 61 patients.

We included patients undergoing bilateral LASIK for myopia and myopic astigmatism, aged between 18 and 39 years (prepresbyopic age group) and patients having stable refraction for a period of 6 months. Exclusion criteria were patients with age more than 40 years (presbyopic age group), any previous ocular surgery, any neurologic or systemic disease, ocular comorbidities such as corneal degeneration and dystrophies, dry eye, corneal opacities and scarring, advanced glaucoma, uveitis, retinal abnormalities involving the central retina, optic nerve diseases, amblyopia and inability to read or understand written English.

Informed consent was taken from willing patients who fulfilled the inclusion criteria. Detailed history regarding any pre-existing ocular inflammations and all the aforesaid ocular and systemic conditions in the inclusion and exclusion criteria was taken. Ocular examination included measurement of UCVA, with pinhole visual acuity and best corrected visual acuity for distance and near, using the LogMAR chart was done both pre- and postoperatively. Detailed ophthalmological examination using slit lamp and dilated fundus examination using +90D and +20D was done to rule out any posterior segment pathology. Pre-operative evaluation also included refraction, corneal pachymetry and corneal topography.

Patients completed the QIRC questionnaire 1 month before and after undergoing LASIK. The questionnaire consisted of 20 questions and the final score was calculated by adding the scores on individual questions and then dividing by the number of questions answered. Patients were required to answer all questions on a 5-point response scale with evenly spaced descriptors. The total QIRC score was divided into four categories as follows: Vision-related score (questions 2–7 and 10–13), glare-related score (question 1), financial-related score (questions 8–9) and psychosocial score (questions 14–20). The score for each category was calculated by adding the scores on individual questions in that category and dividing by the number of questions answered in the same category. A higher score indicated better QoL.

LASIK was planned to achieve complete emmetropic correction. It was performed under topical anaesthesia using the Nidek EC-5000 excimer laser and the Moria microkeratome. The same surgeon performed all surgeries. In all eyes, the corneal flap was 130 mm thick; the optical zone was at least 6.0 mm, increased to 0.5 mm greater than the scotopic pupil for pupils over 5.5 mm.

RESULTS

A total of 61 patients were included in the study, of which 36 (59%) were females and 25 (41%) were males. The mean age of the cohort was 25.28 ± 4.66 years. Table 1 shows the demographic data of the patients enrolled in the study.

The mean pre-operative UCVA was 0.89 ± 0.22 in the right eye and 0.88 ± 0.22 in the left eye. The mean pre-operative refraction was −4.02 ± 2.29 in the right eye and −4.05 ± 2.33 in the left eye. The patients were grouped on the basis of their refractive errors into low, moderate and high refractive error groups and the number of patients in each group was 23 (39.0%), 24 (40.7%) and 12 (20.3%), respectively.

Table 2 shows the comparison of pre-operative versus postoperative QIRC scores in the four categories of glare, vision-related, psychosocial and financial aspects. The total QIRC score showed improvement from 38.51±4.62 to 58.06±5.17. The P-value was statistically significant at <0.0001. The glare-related score showed a reduction from 49.72 ± 11.57 to 41.85 ± 9.75 (P < 0.0001). All the other categories showed significant improvement postoperatively.

Table 3 shows the total QIRC scores across different refractive error grades. The net improvement in the QIRC score postoperatively was 17.17 in the low error group, 19.17 in the moderate error group and 26.18 in the high error group. Table 4 shows difference in the QIRC categories based on the refractive errors.

Table 5 shows the gender-based difference in the QIRC scores. The total QIRC score in women showed improvement from 38.18 ± 4.41 to 58.69 ± 4.83, while that in males improved from 38.98 ± 4.96 to 57.16 ± 5.61. There was no statistically significant difference in the QIRC scores in any of the categories.

The total QIRC score in the low refractive error group improved postoperatively from 40.08 to 57.25. The moderate refractive error group showed improvement from 38.63 to 57.80, while that of the high refractive error group improved postoperatively from 35.61 to 61.79. The pre-operative QIRC score was lower in the high refractive error group, showing that the patients with higher refractive errors have a worse QoL. The post-operative QIRC score showed more improvement in those with higher refractive errors as compared to those with low to moderate errors.

Most patients showed significant improvement in QIRC scores postoperatively. Only one patient reported lesser improvement from 37.25 to 47.37 (<2 standard deviation). The improvement was less in the psychosocial aspect of the score. All patients underwent LASIK aiming for full correction, but two patients reported a post-operative vision of 6/9 in one eye, with some residual post-operative refraction correction.

DISCUSSION

Refractive error remains a major cause of treatable visual impairment.^[1] Correction of refractive error by spectacles and contact lenses makes the patient dependent on that mode of correction and affects the QoL of the individual.^[8] The newer modes of correction of refractive errors by refractive surgeries significantly improve the QoL, as shown by many studies using different questionnaires.^[8-14]

We studied patients in the pre-presbyopic age group between 18 and 39 years of age. The mean age of our patients was 25.28 ± 4.66 years – slightly younger than that found in a study conducted by Hays et al.^[9] (30.2 ± 4.5 years), by Shams et al.^[8] (26.06 ± 2.01 years) and Han et al. (30.47 ± 6.25).^[13]

The number of male patients enrolled in the study was 25 (41%) and that of females was 36 (59%). The number of females undergoing LASIK was found to be more than males, which is consistent with the findings from previous studies.

The gender distribution was similar to the study conducted by Garamendi et al.^[10] (61% females and 39% males). In the study conducted by Shams et al.,^[8] the female group, 63.4%, used spectacles or contact lenses and 17.9% underwent refractive surgery, while in the male group, 69.4% wore spectacles or contact lenses and 9.4% underwent refractive surgery.

In our cohort, the mean pre-operative refractive error was −4.02 ± 2.29 in the right eye and −4.05 ± 2.33 in the left eye. Han et al. reported a pre-operative refractive error of −7.99 ± 2.52 in the right eye and −8.15 ± 2.50 in the left eye.^[13] The mean UCVA preoperatively was 0.89 ± 0.22 in the right eye and 0.88 ± 0.22 in the left eye.

Of the 61 patients, 39% had low refractive error, 40.7% had moderate, while 20.3% had a high refractive error. Garamendi et al.^[10] also classified refractive error in the same manner and the number of patients in the low, moderate and high error groups were 53%, 38% and 9%, respectively. Thus, our study had more patients in the high refractive error group as compared to this study.

The QIRC questionnaire used in this study was developed using Rasch analysis and validated by Pesudovs et al.^[7] A thorough literature search informed a 90-item pilot questionnaire, further reduced to 20 items using data obtained from a pilot study in 306 subjects. The results of the study showed that the questionnaire was valid and reliable for evaluating the QoL in people in the pre-presbyopic age group with refractive correction in the form of spectacles, contact lenses and refractive surgery.

In the present study, QIRC scores were calculated up to 1 month before and after LASIK. The total score was divided into glare-related score, vision-related score, psychosocial score and financial score. The mean pre-operative QIRC score was 38.51 ± 4.62, improving significantly after LASIK to 58.06 ± 5.17 (P < 0.0001). Han et al. reported a total QIRC score of 45.09 ± 5.65 postoperatively in their LASIK group in the study.^[13]

The glare-related score showed a significant reduction from 49.72 ± 11.57 to 41.85 ± 9.75 (P < 0.0001). This departs from previous findings by Shams et al. and Garamendi et al.^[8,10] In the study conducted by them, there was no significant difference seen in the glare-related symptoms postoperatively. In a study conducted by Shams et al.^[8] using the NEI/RQL-42 questionnaire, there was no significant difference found in the glare-related symptoms postoperatively. However, our findings are in concurrence with those of Tahzib et al.^[11] who used a validated questionnaire consisting of 66 items. In their study, the mean score for glare was 3.0 ± 0.9. At night, glare from lights was believed to be more important than before surgery by 47.2%. Glare from oncoming car headlights after surgery was reported by 58.4% and was believed to be more bothersome for night driving than before surgery by 52.8%. Night driving was rated more difficult than before surgery by 39.4%, whereas 59.3% had less difficulty driving at night. All the other categories showed significant improvement postoperatively in their study. As per Han et al., the LASIK group had a glare score of 40.65 ± 10.46, and SMILE had a better glare-related outcome with a score of 46.32 ± 10.^[13]

Several other studies also showed significant improvement in the overall QOL postoperatively. In the study conducted by Garamendi et al.,^[10] the overall QIRC score showed improvement from 40.07 ± 4.30 to 53.09 ± 5.25. The score was not divided into categories; instead, the score of each item on the questionnaire was analysed. All the parameters assessed showed significant improvement postoperatively, except the questions about glare, eye strain and a few psychosocial questions.

Chen and Manche used a new questionnaire called the RSVP score or refractive status and vision profile scores, consisting of 42 items that evaluated different aspects of daily life, such as visual symptoms, activity limitations, dependence on correction and emotional well-being, which improved significantly from a mean of 30.9 points at baseline to 20.7 points 1 year postoperatively.^[14]

In a study conducted by Shams et al.,^[8] the NEI/RQL-42 was used to compare the QoL between myopic patients with spectacles and contact lenses and patients who have undergone refractive surgery. The post-operative score in those undergoing refractive surgery showed significant improvement to 86.98 ± 4.73 as compared to the patients using spectacles or contact lenses, having a mean score of 78.30 ± 9.21. The studied groups showed a statistically significant difference in all 13 subgroups of vision-related QoL postoperatively, except the glare-related score.

There was no significant difference noted in the QIRC scores between males and females in this study. In a study conducted by Garamendi et al.,^[10] women reported significantly worse pre-operative scores (mean 39.06 ± 4.54) than men (mean 41.68 ± 3.51) (P < 0.05). Women reported a better overall QIRC score after refractive surgery than men (mean 53.83 ± 5.46 compared with 49.39 ± 5.94; P < 0.005).

CONCLUSION

This study gave us an insight into how the QoL of the people living with refractive errors was affected. There was no significant difference in the QoL improvement between males and females, although the number of females undergoing refractive surgery was more than that of males. On the QIRC questionnaire, the mean vision-related score, psychosocial score and financial aspect score showed improvement postoperatively. However, glare-related symptoms increased postoperatively, causing difficulty in night driving. The overall QoL of patients with higher refractive errors was found to be lower preoperatively as compared to the low and moderate refractive error groups. Thus, refractive surgery in patients having high refractive error is more beneficial as their QoL showed a drastic improvement post-surgery. The evaluation of the impact of refractive surgery on QoL is important as it helps in understanding the effectiveness of the surgery from the patient’s perspective and provides us with areas that need further research and development.