We conducted a cross-sectional study between June 2020 and August 2020 involving patients attending the glaucoma clinic of Hospital Universiti Sains Malaysia (HUSM). HUSM is one of the tertiary eye care centres in the state of Kelantan, Malaysia. Kelantan is situated in the northeast of Malaysia, with an estimated population of 1.95 million [19 ].
During the three-month period from June through August 2020, we recruited all patients with glaucoma who attended our glaucoma clinic. Our inclusion criteria were confirmed cases of glaucoma with at least three previous visits within a year prior to March 18, 2020, and a pre-MCO IOP and best-corrected visual acuity (BCVA) recorded. We excluded those who were diagnosed with ocular hypertension, primary angle closure (PAC), or primary angle closure suspects (PACS). We also excluded those with pre-existing optic neuropathies.
We included 221 patients in the preliminary recruitment phase, and we traced their medical records. We excluded 27 patients from the final recruitment due to an inadequate number of pre-MCO follow-ups (19 patients) or because the IOP and BCVA were taken more than four months prior to MCO (eight patients). We obtained the pre-MCO IOP and BCVA from the medical record.
A thorough ocular examination was conducted, including slit-lamp biomicroscopy examination, fundus examination, and IOP measurement. Trained staff nurses did a visual acuity assessment using the Snellen chart. BCVA was included in our analysis. We used Goldmann applanation tonometry (Haag-Streit, Switzerland) to measure the IOP. A fundus examination was conducted using a 90D lens (VOLK, USA). Two experienced glaucoma specialists performed the vertical cup-to-disc ratio (VCDR) assessment. We recorded four clinical outcomes, which include missed medication, change of treatment, hospital admissions, or no change in treatment.
Missed medication was recorded when the patient was out of medication for more than two weeks prior to the recruitment period. A change of treatment was defined as any addition, switching, or changing of topical pressure-lowering drugs for uncontrolled IOP or failure to reach target pressure. Admission for uncontrolled IOP refers to any admission to the hospital due to uncontrolled IOP during the recruitment period. No change in treatment was when the target pressure was achieved without missing medication.
Primary open-angle glaucoma is a chronic progressive optic neuropathy with characteristic morphological changes at the optic nerve head and retinal nerve fibre layer, in the absence of other ocular disease or congenital anomalies. Angle-closure glaucoma is defined by the presence of iridotrabecular contact. A secondary glaucoma is a heterogeneous group of conditions, in which elevated IOP is the leading pathological factor causing glaucomatous optic neuropathy, either being open or closed angle [20 (link)]. We defined pre-MCO IOP and BCVA as the last IOP and BCVA taken no longer than four months prior to the MCO.
We performed our statistical analysis with the Statistical Analysis Software Package (SPSS), version 26 (SPSS Inc., Chicago, IL). We conducted double entries of the data to avoid incorrect entries or missing data. We analysed categorical data using the Pearson chi-squared test. We analysed numerical data such as IOP and VCDR using a paired t-test. A p-value of less than 0.05 was considered statistically significant.
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