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Year : 2015  |  Volume : 3  |  Issue : 2  |  Page : 87-90

Difficulties with self instillation of eye drops and its impact on intraocular pressure in glaucoma patients

1 Department of Pharmacology, Maharaja Agarsain Medical College, Agroha, Haryana, India
2 Department of Pharmacology; Radhaswamy Eye Hospital, Barwala, Hissar, Haryana, India
3 Department of Population Polices & Programmes, International Institute for Population Sciences, Mumbai, India

Date of Submission03-Feb-2014
Date of Acceptance14-Oct-2014
Date of Web Publication7-May-2015

Correspondence Address:
Parveen Rewri
Department of Ophthalmology, Maharaja Agarsain Medical College, Agroha, Hissar-125047 Haryana
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2320-3897.156592

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Aims: Prevalence of glaucoma increases with age and this potentially blinding condition requires regular instillation of eye drops. But with aging itself and accompanying co-morbidities, self instillation of eye drops gets affected. This study was designed to study the subjective difficulties associated with self instillation of eye drops in glaucoma patients and to quantitatively assess their impact on intraocular pressure (IOP). Settings and Design: Prospective interventional study at primary eye care center. Materials and Methods: A total of 69 persons diagnosed with glaucoma or ocular hypertension (OHT), who were self instilling their eye drops, were included in this study. Patients were interviewed for subjective difficulties being faced during self instillation using a formatted questionnaire. The patients were then subjected to assisted eye drop instillation for 4 weeks. The change IOP and consumption of eye drop bottles were compared between self installation and assisted instillation periods. Statistical Analysis: Paired t-test was applied at 5% significance level to compare pre and post interventional change of parameters. Results: Fifty three percent of patients reported subjective difficulties while self instilling their eye drops. Non-compliance was self-reported in 18% of the patients. The IOP dropped by 10-13% (P-value < 0.0001) and consumption of eye drop bottles was 14% (P-value < 0.0001) higher during self instillation. Conclusion: Assisted eye drop instillation may be beneficial to achieve better IOP control.

Keywords: Assisted instillation, eye drops, glaucoma, intra-ocular pressure, self instillation

How to cite this article:
Virani S, Rewri P, Dhar M. Difficulties with self instillation of eye drops and its impact on intraocular pressure in glaucoma patients. J Clin Ophthalmol Res 2015;3:87-90

How to cite this URL:
Virani S, Rewri P, Dhar M. Difficulties with self instillation of eye drops and its impact on intraocular pressure in glaucoma patients. J Clin Ophthalmol Res [serial online] 2015 [cited 2023 Mar 24];3:87-90. Available from: https://www.jcor.in/text.asp?2015/3/2/87/156592

Topical medications have an important role in the treatment of glaucoma. The current therapeutic approaches are centered on reducing intraocular pressure (IOP) [1] , the only known modifiable risk factor. Topical medications are usually the first line therapy offered for reducing IOP [2] and in many glaucoma patients' medications alone can control the disease. The IOP control with topical medication (s) is influenced by several physiological and non-physiological factors. [3],[4],[5],[6],[7] In order to achieve desired therapeutic response proper instillation of topical medication is important Proper instillation of eye drops essentially includes compliance and performance. Performance,the ability of correctly instilling the eye drop, [8] is affected by number of factors such as age [9] , visual acuity and presence of co-morbid conditions. [10] Several studies have shown that patients experience difficulties in self-instillation of their eye drops. [8],[11] The difficulties associated with self instillation of eye drops from commercial bottles have been acknowledged and novel techniques, designs and aids have been proposed. [5],[12],[13],[14] These aids are helpful in facilitating self instillation, but are limited by requirement of correct technique [15] , physical force [16] dispensing, cost, availability and comprehension.

The present study was designed to identify the difficulties associated with self instillation of eye drops among rural glaucoma patients and assess its impact on IOP control and consumption of eye drops.

  Materials and Methods Top

The prospective, interventional study, done between September 2009 and November 2010, involved 69 patients of glaucoma or ocular hypertension. Enrollment of eligible persons was done after obtaining consent for participation to study protocol and use of information for publication in scientific literature. The study was approved by ethics sub-committee of the hospital and adhered to the tenets of the declaration of Helsinki.

Patients of glaucoma or ocular hypertension, aged between 18-80 years, who were self-instilling their anti-glaucoma topical medicine were invited to participate in this study. Glaucoma was defined as presence of glaucomatous optic nerve head (ONH) changes with corresponding visual field defects. Office hour recording of IOP more than 22 mmHg on at least more than two occasions with central corneal thickness between 500-550 microns, in absence of glaucomatous ONH or visual field changes was defined as ocular hypertension Patients self instilling their eye drops despite bilateral poor visual acuity (< 6/60 in both eyes) or unilateral blindness (absence of perception of light in one eye) were also allowed to participate. Exclusion criteria included presence of generalized or localized motor disorder affecting hand to eye co-ordination such as Parkinsonism; disease conditions with impaired memory and titration of doses or change of medication regimen to achieve IOP control during study period. The enrolled participants underwent a comprehensive ophthalmic examination. During enrollment visit, technique of self instillation was demonstrated by an ophthalmic assistant to ensure participants knew the correct way of self instillation of their eye drops. These patients were instructed for self instillation of their topical anti-glaucoma medicine for next 4 weeks. Enrolled patients were provided a folder containing a pictorial guide of correct technique of self instillation of eye drops and dose calculator sheet (DCS), to track the eye drop instillation. The DCS had boxes each for missed doses and doses instilled by someone else, if any; for each calendar day. The participants had to mark the same if they missed any scheduled dose or if someone else instilled the eye drop dose. A new bottle of topical medicine of same brand which patient was using was given to assess consumption of eye drops during period of self instillation. On first visit after 4 weeks of self instillation, the Goldmann applanation (GAT) IOP was recorded by taking three readings at interval of 2 hours to minimize the diurnal variation. A standard format questionnaire was used to probe problems faced during self instillation. It included specific inquiry into difficult targeting, extra drop squeeze, and difficulty in squeezing the bottle, shaking hands and missing doses.

Patients were then switched to assisted instillation of topical anti glaucoma medicine for 4 weeks and new bottles of medicine were provided. The care taker accompanying the patient was demonstrated the method of instillation of the eye drop, and a folder containing pictorial guideline for eye drop instillation technique and DCS was provided. The DCS was provided to record missed doses and to record self instilled doses. At the end of 4 weeks of assisted instillation, GAT-IOP was recorded by taking three readings at interval of 2 hours.

The topical medication consumed was calculated by counting the empty bottles. For half used bottles, numbers of drops left out in eye drop vial were collected using disposable syringes. This residual volume was subtracted from the original dispensed volume in eye drop bottles, to get the consumed amount. The cost analysis was done using the prevalent maximum retail price (MRP) and the unit price for each ml was calculated from the MRP for dispensed volume.

The cut off for protocol deviation that is, assisted instillation during self instillation period or vice versa, was arbitrarily fixed to 95% of the total doses between enrollment and second visit. The window period for scheduled follow-up visits was ± 3 days. A clinically significant non-compliance was fixed for more than two doses missed per week. [17]

Descriptive statistics were worked out to assess the difficulties arising in self instillation. To assess the level of IOP and the number of bottles used during self and assisted instillation, mean and standard deviation (SD) were estimated. The confidence intervals (CI) for proportion were computed using modified wald method. To compare the same among themselves, paired t-test was applied at 5% level of significance. Data was statistically analyzed using SYSTAT 13 package.

  Results Top

Out of sixty nine patients initially enrolled for participation, eight (12%) did not turn up within window period of scheduled follow-up, five (7%) deviated from the study protocol and two (3%) had self-reported, clinically significant non-compliance. Demographic and diagnostic data is summarized in [Table 1]. Seven patients (13%; 95% CI: 6-24) had underwent filtration surgery in past and were on medical therapy for achieving target IOP. The uncorrected visual acuity in the better eye ranged from 6/5 to 5/60 on Snellen's charts and the mean best corrected visual acuity in better eye was Log MAR equivalent of 0.57 ± 0.8. The average mean deviation (MD) of affected eyes on SAP automated perimetry was -11.68 ± 8.23 db.
Table 1 Demographic and diagnostic characteristics of the Study participants

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Forty seven (87%) patients were instilling topical medication in both the eyes and seven (13%) in only one eye. Sixteen patients (29%) were instilling once a day, twenty three (43%) twice a day, seven (13%) thrice a day and eight patients (15%) were instilling five times a day. Average number of instillations per person per day was 2.5 ±1.24 (95% CI: 2.1-2.8).

Subjective difficulties were reported by twenty nine (53%; 95% CI: 40-66) participants, out of which 26 (48%; 95% CI: 35-61) reported multiple difficulties. The most common problem encountered during self instillation was difficulty in targeting the eye drop to eye, reported by 18 (33%; 95% CI: 22-47) patients. Subjective difficulties reported by the participants included inadvertently touching the bottle tip to eye, problem in identifying the scheduled eye drop in cases using multiple eye drops, difficulty in capping the bottle after instillation, extra drops expression and cumbersome multiple instillation [Figure 1]. The subjective difficulties were more frequent among those aged above sixty years; however difference was not statistically different (P = 0.229). Subjective difficulties in maneuvers requiring physical force or better hand to eye coordination such as targeting and squeezing the bottle showed an increasing trend with age [Figure 2], others like forgetfulness about scheduled doses was not significantly related to age (0.3). There was no statistically significant relation with visual acuity in better eye and frequency of subjective difficulties (P = 0.067).
Figure 1: Frequency distribution of subjective difficulties on self instillation of eye drops-(A) Difficult targeting (B) Difficult squeezing (C) Eye -Tip touch (D) Extra drop expression (E) Difficult capping (F) Cumbersome frequent instillation (G) Dose forgetfulness

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Figure 2: Age wise trend of subjective difficulties

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The mean IOP after 4 weeks of self-instillation were 17.19 ± 3.68 and 16.91 ± 2.52 mmHg, respectively in right and left eye. After the 4 weeks of assisted instillation the mean intraocular pressures were 15.58 ± 3.63 and 14.99 ± 2.70 mmHg, respectively in right and left eye. The mean IOP was significantly lowered (P < 0.0001) by 1.61 (95% CI: 1.22-2.00) mmHg in right eye and 1.92 (95% CI: 1.35-2.48) mm Hg in left eye on assisted instillation.

The average number of bottles consumed per person during self-instillation period was 2.24 ± 0.79, and was 1.88 ± 0.71 during assisted instillation. There was mean reduction of 0.35 (95% CI: 0.20-0.50) bottles per person (P = < 0.0001) owing to assisted instillation and cost saving percentage was 16% (95% CI: 10-23) at prevailing cost of topical medicine.

  Discussion Top

The present study is probably the first one in India which quantitatively investigated the impact of self-reported subjective difficulties on IOP. Previous studies examined self-reported problems [18] and compliance barriers. [19] Assisted instillation of eye drop may be required in glaucoma patients depending upon age, visual acuity, and general health, cognition ability and comprehension of individual and perhaps prevailing socio-cultural practices in community. In most cases, individuals instill their eye drops themselves. [20] Self instillation of the eye drops has been reported to be faulty in many studies. [19],[21],[22] Gupta et al.,[19] found that only nine percent of individuals were able to correctly instill the eye drop. However, most patients are unaware of the faulty techniques and often claim to have no difficulty whatsoever in self instillation. [21]

Difficulties associated with self instillation have been widely studied. [9],[17],[18],[19],[20],[21],[22] Most common problems reported by patients in our study included targeting the eye drop, squeezing the bottle, forgetting to instill drop in time, extra-drops instillation, and difficulty in puncturing the bottle entry. These have been noted in previous studies also. [19],[23] Burns et al.,[22] reported that majority of elderly, experience difficulty or have an unsuccessful self instillation. Poor compliance has also been associated with self instillation [24] which may lead to therapeutic failure. [23] Ashburn et al.,[25] estimated that at least ten percent of glaucomatous blindness is due to poor compliance. Self-reported non-compliance, although, was an exclusion criteria in our study, accounted for just three percent. Subjects participating in a study or survey often tend to show better compliance. Novack et al.,[26] found up to thirty percent improvement in compliance in glaucoma patients participating in a study. Thus, the estimates of non-compliance may always be conservative ones.

Improper installation of eye drops may result in therapeutic under effect. Konstas et al.,[17] reported over 4 mmHg of higher mean IOP in non-compliant patients. However, base line pressure of these two groups was not discussed. In our study during assisted instillation of the eye drop we found additional drop of mean IOP, which is both statistically and clinically significant. Importance of drop of each mmHg needs not to be emphasized. Major trials demonstrate that each millimeter reduction of IOP decreases the risk of progression by 10-16 percent [27],[28],[29] Inadequate control of IOP related to persistency or compliance is underestimated by clinicians and patients [30],[31] , and most often IOP is presumed to be uncontrolled leading to addition of add on drops.

The result of our study re-enforces the need to understand and give appropriate attention to the issue of eye drops instillation. Lacy et al.,[23] identified requirement of additional assistance for instillation of their eye drops in patient aged above 60 years. Self instillation can be difficult for elderly persons and this may be more troublesome in glaucoma patient with depression of fields; more so in presence of other vision hampering ocular conditions. Improper drop instillation is equivalent to pseudo-compliance and may result in poor pressure control despite an impression of compliance both with treating ophthalmologist and patient.

This study is not without limitations. First, numbers of patient in the study group were small. Secondly, though, we tried to monitor patient's compliance to study protocol and drug instillation indirectly through the daily dose calendar, but fact remains that it is self-reported compliance to protocols. Additionally it is possible that it could have affected compliance positively. Third, the IOP is a dynamic variable and is affected by number of factors including technique of eye drop instillation as discussed in the present study. We tried to minimize other confounding factors such as diurnal fluctuation by taking mean of multiple IOP readings at different times. Fourth, additional crossover of the study participants can enhance the validity of results. And lastly drop out was large (12%) among participants.

The study results do not endorse assisted instillation in all patients, as it may not be practically feasible. But we recommend that assisted instillation should be helpful for the patients where difficulty with self instillation is expected. It may also be given a try in patients where expected therapeutic response has not happen, before switching to other drug or adding another drug.

  References Top

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