Factors influence bullous keratopathy post cataract surgery at National Eye Center of Cicendo Eye Hospital (PMN RSMC), West Java, Indonesia

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INTRODUCTION
Bullous keratopathy is one of the leading causes of vision loss following cataract surgery. 1 Several causes of bullous keratopathy are cataract surgery with or without intraocular lens (IOL) implantation, primary or secondary rejection of corneal graft, absolute glaucoma, and corneal endothelial dystrophy (Fuch's dystrophy). 2 As much as 60% of bullous keratopathy is caused by iatrogenic factor, in which cataract surgery is the most common cause for either pseudophakic or aphakic bullous keratopathy. 1,2 Pseudophakic bullous keratopathy represents the final clinical presentation of corneal opacification, characterized by the presence of bullae in corneal epithelium due to loss of corneal endothelial function. 3 Comprehension about this disease is required for proper management, considering the incidence of pseudophakic bullous keratopathy (PBK) is estimated to be 0.1% in patients undergoing cataract surgery in United States. 3- 6 The onset of pseudophakic bullous keratopathy and aphakic bullous keratopathy vary from months to several years following cataract surgery. 3,4 This condition begins with severe corneal edema after cataract surgery and may persist or worsen. Corneal edema starts from the superior or peripheral and temporal cornea with subsequent spread to the central cornea thus causing decreased visual acuity. The early process of corneal edema may cause discomfort without decreased visual function, but with progressively increasing severity it can cause periodic and persistent pain. 4,7 Damage to the cornea accumulated before, during, and after cataract surgery contributes to the development of bullous keratopathy as the number of corneal endothelial cells reduces. Contributing factors for pseudophakic and aphakic bullous keratopathy have been well-studied. 1,4,7 This study aimed to describe the pre-, intra-, and postsurgical factors relating to the occurrence of bullous keratopathy after cataract surgery at the National Eye Center of Cicendo Eye Hospital in West Java, Indonesia.

METHODS
This was a retrospective descriptive study using data extracted from patient medical records. Patients diagnosed with bullous keratopathy after cataract surgery who underwent further examination

RESULTS
From the total of 26 patients included in this study, 14 (53.85%) of which underwent cataract surgery at Cicendo Eye Hospital, while the remaining 12 (46.15%) had surgery performed in other locations ( Table 1). The study population was slightly predominated by elderly (57.69%) females (57.69%). Further analysis would include variable numbers of patients who fulfilled predetermined eligibility criteria especially in data completeness. An identical proportion of the patients had preoperative visual acuity of 1/60-3/60 and less than 1/60, while all patients had normal preoperative IOP ( Table 2). Half of the patients had normal cornea and the most frequent manifestation of preexisting corneal haziness was corneal cicatrix. The proportion of patients increases with the increase of cataract grading. The majority of patients had hypertension or diabetes comorbidity (64.29%).
Postoperative clinical characteristics in Table  4 were tabulated based on the location where the cataract surgery was performed. Generally, the postoperative visual acuity was less than 1/60 and the surgery was uneventful. However, it was observed that the proportion of patients with visual acuity less than 1/60 was higher in other locations. All patients maintained normal IOL, despite sustaining microbullae. A small number of patients (14.28%) experienced uveitis and IOL adhesion to the endothelial surface as postoperative complications.

DISCUSSION
Advancements in cataract surgical procedures have improved the outcome considerably alongside its increasing trend worldwide. 8 Inversely proportional decrease in the surgical adverse effects did not preclude the possibility. Previous studies observed the complication rate difference by numerous factors, which can be categorized in pre-, intra-, and postoperative timeline. 9 Despite the seemingly ORIGINAL ARTICLE low incidence of bullous keratopathy (1-2%) as one of the complications, it is important to consider that the multiplier or the cataract surgery rate is ever-growing. 10 Existing literature investigating contributing factors of bullous keratopathy after cataract surgery was lacking, and to the best of our knowledge, this is the first study attempting to address this particular complication.
The loss of corneal endothelial cells in surgical trauma was identified as the principal cause of bullous keratopathy. 10 Intriguing findings by Inomata et al. 11 revealed that corneal thickness depended on age, sex, and body size in mice. The thickness initially increased up to a certain extent before continuing to decline in spite of increasing body size. Additionally, an interspecies allometric analysis found a significant correlation to humans. Studies in human subjects confirmed these findings. Central corneal thickness, endothelial cell density, and hexagonality were lower in the aging population. Furthermore, corneal variability was also reported between races. [12][13][14] In this study, the difference in proportion of age and gender may affect the patients' surgical outcome. Although thorough preoperative assessment did not affect the postoperative outcome, 15 identification of comorbidity at risk, such as diabetes, was crucial in avoiding bullous keratopathy. 16 Phacoemulsification and MSICS were regarded to have similar efficacy and safety profile in treating age-related cataract. 17 Preference of one over the other may be adjudicated by cost or resource reasons. Similarly, the purpose of cohesive or dispersive agent was chiefly influenced by their respective characteristics. 18 A randomized clinical trial proposed the benefit of balanced salt solution over Ringer's lactate in increasing corneal thickness and improving postoperative inflammation. 19 Combined together, the choice of viscoelastic and irrigation fluid may impact intraoperative rheology and fluidics aspects relevant to the study aim. 20 Detailed stratification of IOL implantation, including the implantation status, implantation site, and IOL material was structured considering the most recent finding of the association between IOL implantation and decrease in endothelial cell density. 21 The proportion of patients with visual acuity of <1/60 increased postoperatively, in conjunction with the total conversion of corneal status into microbullae. Note that half of the patients had corneal opacities due to cicatrix and crocodile shagreen to begin with, which were not detected in the postoperative assessment. The appearance of microbullae probably attributed the lack of expected gain in vision quality. 22 This study had some limitations: small sample size, lack of comprehensive variables, and interobserver variability. There was an absence of data on surgical duration and endothelial cell count and morphology.

CONCLUSION
Bullous keratopathy after cataract surgery was more common in elderly females. There were notable changes in visual acuity and corneal status postoperatively. Further large-scale analytic study