A Cross-sectional Study on Adherence to Topical Glaucoma Medication and its Determinants among Patients Attending Glaucoma Clinics of a Tertiary Care Institute of Ahmedabad City, Gujarat, India

Abstract

Aim and background

Glaucoma is a leading cause of blindness in India, and treatment adherence is essential to prevent vision loss. However, studies have shown that treatment adherence rates among glaucoma patients in India are low. It is important to identify the factors determining treatment adherence in order to improve compliance with the treatment, thereby preventing worsening vision. The current study was conducted with an objective to assess the treatment adherence among glaucoma patients using the Morisky Medication Adherence Scale (MMAS-8) and to assess determinants of treatment adherence among the study participants. A drop instillation technique among the glaucoma patients was also evaluated.

Materials and methods

A cross-sectional study was conducted among primary open-angle glaucoma (POAG) patients at a selected tertiary care institute in Ahmedabad city. The calculated sample size was 100. Glaucoma patients receiving treatment for at least 3 months were enrolled. Systematic sampling was applied, wherein every alternate patient fulfilling the inclusion criteria was selected. After obtaining informed consent, interviews were conducted using a pretested and predesigned pro forma including MMAS-8. Participants were instructed to use sterile artificial tears, which were evaluated by the investigator for precision.

Results

The mean age of study participants was 62.0 ± 6.28 years. Among the participants, 54% were female. The study revealed that 82% of participants had poor adherence to glaucoma medication. Factors such as education, regular follow-up, and having received prior instruction were significantly associated with adherence to medications. Only 43% of the patients were able to instill the eye drops correctly.

Conclusion

Low adherence to medication was found among 82% of cases. Factors significantly associated with adherence were gender, education, duration of treatment, and having received prior instruction. Forgetfulness and the cost of treatment were the most common factors leading to low treatment adherence. Among 79 participants who were observed for the drop instillation technique, 43% were found to have instilled it properly.

How to cite this article

Shah V, Shah D, Desai HP, et al. A Cross-sectional Study on Adherence to Topical Glaucoma Medication and its Determinants among Patients Attending Glaucoma Clinics of a Tertiary Care Institute of Ahmedabad City, Gujarat, India. J Curr Glaucoma Pract 2025;19(3):107–111.

Introduction

Glaucoma, a progressive optic nerve disorder, poses a significant threat to vision globally, standing as the second leading cause of blindness.¹ It is characterized by changes in the optic disk and visual field defects, with a progressive loss of retinal ganglion cells. The common risk factors for glaucoma include raised intraocular pressure (IOP), age, and family history.² Glaucoma is the leading cause of irreversible blindness both globally and in India. It is estimated that about 11 million people in India have open-angle glaucoma (OAG) and another 5 million have closed-angle glaucoma (CAG) in the year 2020.³ However, among these remarkable numbers is a disturbing fact: glaucoma medication adherence is still remarkably low. A study conducted in South India found that 42% of glaucoma patients reported poor medication adherence.⁴

Glaucoma patients usually need lifelong medication and follow-up care to preserve vision. Adherence (or compliance) with a drug regimen refers to how well people follow their doctors' prescriptions when taking their medications.⁵ Many healthcare professionals prefer to use the term “adherence” rather than “compliance,” as the latter implies that the patient is only following orders without actively participating in the treatment plan and that the doctor and patient have not formed a therapeutic partnership or contract. Both terms are imperfect and uninformative descriptions of medication-taking behavior. Generally, glaucoma drug adherence and associated factors are classified into four general groups. These are: patient-related, medication-related, provider-related, and environment-related factors.⁶

Glaucoma treatment adherence is influenced by a variety of factors, such as the number of medications as well as frequency of medication during the day. The patient-provider relationship and communication have been noted as potential barriers to adherence in studies of glaucoma. Older patients may exhibit poor glaucoma treatment adherence due to difficulty reading prescription labels.⁷ One significant reason for suboptimal control of glaucoma is poor medication adherence.⁸ Poor medication adherence has been correlated with both disease severity and progression of the disease.^8,9

Topical ocular pharmacotherapy, one of the key therapies and usually the first therapy used to treat elevated intraocular pressure, depends on patient adherence with the prescribed treatment regimen and patient performance, which is the ability to correctly instill the eye drop. Beyond simply remembering to take their drops, subjects may not be using their eye drops correctly.¹⁰ Unlike oral medicines, eye drops require patients to use proper technique for successful medication administration. This requires not only instilling a single drop accurately into the conjunctiva of the eye, but also without contacting the eye drop container with the ocular surface or adnexa. It has been reported that more than half of the patients omitted 10% of their doses, and 15% of patients omitted half of their doses.¹¹ Over the past decade, although several studies have reported that 25% to 90% of subjects fail to administer their eye drops correctly.^9,10,12–14

Developing effective strategies to manage and prevent glaucoma-related vision loss is an important public health issue. The current study aimed to assess the treatment adherence among glaucoma patients and to determine the factors influencing adherence. The issue related to the correct drop instillation technique was also assessed in the study.

Materials and Methods

Study Design and Setting

A cross-sectional study was conducted among glaucoma patients at a selected tertiary care institute in Ahmedabad city. Patients who had follow-up visits at the Glaucoma Clinic of the hospital during the study period (September–November 2024) were enrolled in the study. Institutional ethics committee permission was sought in advance (Approval no.: GCSMC/EC/Research Project/APPROVE/2024/645 dated 30 January 2024). The study adhered to the tenets of the Declaration of Helsinki.

Inclusion Criteria

All adult patients with the diagnosis of primary open-angle glaucoma (POAG) and who had been on treatment with one or more topical hypotensive medications in one or both eyes for at least the past 3 months.

Exclusion Criteria

Patients who had undergone laser or surgical glaucoma therapy and were on postoperative topical medications such as anti-inflammatory drugs other than glaucoma medication were excluded from the study. Patients not willing to give informed consent were also excluded.

Sample Size

From a previous study conducted in South India, adherence to glaucoma treatment was 42%.⁴ Therefore, using the formula n = 4pq/E², where p = 42%, q = 58%, and E = 10% (absolute error), the sample size turned out to be 98. A sample size of 100 was used for the study.¹⁵

Study Population, Main Parameters, and Data Collection

Primary open-angle glaucoma patients fulfilling the inclusion criteria were enrolled using a systematic sampling method. Written consent was obtained from all participants. Sociodemographic and glaucoma-related information was recorded using a pretested and predesigned pro forma. The Morisky Medication Adherence Scale-8 (MMAS-8) was used to assess treatment adherence.¹⁶ Each item in the questionnaire measured a specific medication-taking behavior and not a determinant of adherence behavior. Response categories were “yes/no” for each item and a 5-point Likert scale for the final item.

Patients were assessed for the correct drop instillation method. Participants were instructed to instill sterile artificial tear drops in the same manner as they would at home. The entire process was observed and assessed by the investigator.

Statistical Analysis

Data entry was done using Microsoft Excel and analyzed using Jamovi software version 2.6.44. The Chi-square test was applied to assess associations. p-values < 0.05 were considered statistically significant.

Results

The mean age of participants was 60.82 years, with a standard deviation of 10.02 years. In terms of gender distribution, 54% of participants were female, and 46% were male. Among participants, 33% reported a family history of glaucoma, while 67% did not. Regarding duration of topical intraocular pressure (IOP)-lowering medication use, 28% had used it for less than a year, while 72% had used it for over a year. By education level, 11% were illiterate, 35% had primary education, 37% had secondary education, and 17% were graduates. Regarding prior drop instruction, 58% reported receiving it, while 42% did not. The socioeconomic classification was: 11% upper class, 36% upper middle class, 22% middle class, 24% lower middle class, and 7% lower class (Table 1).

Table 1.

Sociodemographic characteristics of study participants (N = 100)

Variables	Percentages
Age (Years)
≤60	48
>60	52
Gender
Female	54
Male	46
Family history of glaucoma
Yes	33
No	67
Duration of prior use of topical IOP-lowering
<1 Year	28
>1 Year	72
Education
Illiterate	11
Primary	35
Secondary	37
Graduate	17
Previous drop instructions
Yes	58
No	42
Socioeconomic status
Upper class	11
Upper middle class	36
Middle class	22
Lower middle class	24
Lower class	7

Table 2 shows factors associated with glaucoma adherence. There was a statistically significant association between gender and adherence. Education level also showed a significant association (p = 0.001), with higher adherence observed among graduates compared to illiterate participants and those with primary or secondary/higher secondary education. Family history of glaucoma did not show a significant association (p = 0.603). Participants who received instruction regarding drug use demonstrated higher adherence compared to those who did not (p < 0.001). Duration of treatment was significantly associated with adherence (p < 0.001). The number of drugs prescribed did not show a significant association with adherence (p = 0.49).

Table 2.

: Factors associated with glaucoma drug adherence (N =100)

Variables	Adherence		Chi-square (p-value)
	Low n (%)	Medium or high n (%)
Age (years)			1.892 (0.169)
≤60	42 (87.5)	6 (12.5)
>60	40 (76.92)	12 (23.08)
Gender			18.699 (<0.0001*)
Female	36 (66.67)	18 (33.33)
Male	46 (100)	0
Education			57.67 (0.001*)
Illiterate	11 (100)	0
Primary	33 (94.29)	2 (5.71)
Secondary/Higher-secondary	35 (94.59)	2 (5.41)
Graduate and above	3 (17.65)	14 (82.35)
Family history of glaucoma			0.271 (0.603)
Yes	28 (84.85)	5 (15.15)
No	54 (80.60)	13 (19.40)
Instruction received regarding use of drugs			15.39 (<0.001*)
Yes	55 (94.83)	3 (5.17)
No	27 (64.29)	15 (35.71)
Duration of treatment			24.046 (<0.001*)
< 1 year	22 (100)	0
1–3 years	23 (100)	0
3–5 years	21 (80.77)	5 (19.23)
>5 years	16 (55.17)	13 (44.83)
No. of drugs prescribed			0.479 (0.49)
Single drug	57 (83.82)	11 (16.18)
Multiple drugs	25 (78.13)	7 (21.88)

Figures in parentheses are row-wise percentages, *significant p-values

Morisky Medication Adherence Scale-8 in glaucoma patients showed that 82% of participants had low adherence, 11% had medium adherence, and 7% had high adherence to glaucoma medication (Fig. 1).

Fig. 1.

Morisky Medication Adherence scores in glaucoma patients (N = 100)

Among the 79 participants who were observed for the drop instillation technique, 43.03% used it correctly, whereas 56.97% used an incorrect technique (Fig. 2).

Fig. 2.

Assessment of drop instillation technique (N = 79)

Discussion

The findings of this study shed light on the critical issue of treatment adherence among glaucoma patients, a population that is especially vulnerable to visual loss if not properly controlled. The Morisky Medication Adherence Scale (MMAS-8) was used in the study to assess glaucoma medication adherence, providing useful insights into the factors impacting adherence rates as well as the study participants' competence with drop instillation techniques.

The study revealed a high prevalence of low adherence (82%) to glaucoma medication among the participants. The finding was considerably higher than that observed by Killeen et al.⁴ (42%) from South India. Singh et al.¹⁷ also reported similar findings, with around 32% of patients having poor adherence. Sociodemographic differences and differences in assessment methods might account for such variation. Education level was found to be a major predictor of adherence. Participants with higher education, particularly graduates, showed greater adherence (14 participants, 82.35%) than those with lower levels of education.

In the current study, gender was significantly associated with adherence, with 33.33% of females and none of the males exhibiting medium or high adherence. This contrasts with some studies that found no significant gender differences in adherence rates.⁹ Another notable finding was the significant association between receiving prior instruction regarding drug use and adherence to glaucoma medication. Participants who received instructions on medication use demonstrated higher adherence levels compared to those who did not receive such instructions. Sleath B et al.¹⁸ reported in their study that patients receiving more education regarding glaucoma were more likely to take their glaucoma medication doses on time.

Furthermore, the study assessed drop instillation techniques across participants, demonstrating inadequate proficiency in eye drop administration. Only 43% of participants could appropriately administer eye drops, indicating a gap in patient knowledge and skills regarding proper drop administration. A study by Gupta et al.¹² in Delhi showed that only 8.57% of participants were able to correctly instill the eye drops. Another study by Gomes et al.¹⁹ in Brazil showed that 28% of participants were able to correctly administer eye drops. A study conducted by Feng et al.²⁰ indicated that an instructional video on proper eye drop instillation technique increases the proficiency of glaucoma patients.

Limitations of the Study

Being a cross-sectional study, it captures adherence at a single time point, limiting the ability to assess changes over time. Self-reported adherence using the MMAS-8 scale may introduce recall and social desirability bias. Additionally, the study was conducted in a single tertiary care center, which may limit the generalizability of findings to broader populations.

Conclusion

This study highlights the critical issue of poor adherence to glaucoma medication, with 82% of participants exhibiting low adherence as assessed by the MMAS-8 scale. Education level and prior instruction on drug use emerged as significant determinants of adherence, reinforcing the importance of patient education and counseling. While a longer duration of treatment was associated with better adherence, family history of glaucoma and the number of prescribed medications did not significantly influence adherence.

Additionally, the study revealed a considerable gap in the correct instillation of eye drops, with more than half of the participants demonstrating incorrect techniques. Given the progressive and often asymptomatic nature of glaucoma, these findings underscore the need for targeted interventions, including patient education, regular counseling, and training on proper medication administration.

Clinical Significance

This study has significant clinical implications in glaucoma management, highlighting the high prevalence of poor medication adherence among patients. The study emphasizes the need for structured patient counseling and educational interventions for improving adherence. The finding that over half of the participants demonstrated incorrect eye drop instillation underscores the necessity of hands-on training during clinical visits. Implementing adherence assessment tools, patient education programs, and reminder systems can help improve compliance, ultimately reducing the risk of glaucoma-related vision loss.

Orcid

Venu Shah https://orcid.org/0000-0003-4133-582X