Effects of general anesthesia on ocular Refraction: An observational study

Abstract

Refractive error is an ocular condition whereby light rays do not focus onto the macula for visual processing when they enter the eye. The most prevalent type, myopia, often known as short sightedness, is brought on when light rays entering the eye are focused anterior to the macula, blurring distance vision. Though rare, there are few situations that can call for the introduction of performing objective ocular refraction under GA. Refractive testing under general anesthesia (GA) is more safely suited for patients with conditions like subjective difficulty with charts, poor testing cooperation, nonorganic visual impairment refractions, physically or developmentally disabled patients, and those with co-existing ophthalmic pathology. A 2-week prospective observational study was conducted in our hospital to look at the anesthetic methods used for ocular surgery at two sizable ophthalmic units. The anesthetist filled out a questionnaire for each case. The types of anesthetics used, the choice of ventilation or spontaneous respiration, the anesthetic agents used, the use and type of muscle relaxants, the presence of any significant ocular deviation, and any corrective actions taken, such as deepening anesthesia or giving a muscle relaxant, were among the information gathered.90 procedures in all were surveyed within the 2-week period. 52.2% (47) of them anesthesia was provided by consultant anesthetist, 25.6% (23) provided by Anesthesia Post Graduate Trainee(PGT) and 22.2% (20) provided by specialist registrar anesthesia. 74% (23) of the patients with NDMR out of the total 59% (31) ventilated patients had NDMR. 42% (22) of the patients had surgery done while they were spontaneously breathing, and 14% (3) of them had muscle relaxants to help with intubation. Total intravenous anesthesia was administered to one patient. In the poll, 29% (15) of the patients chose atracurium as their preferred NDMR, whereas 21% (11) chose vecuronium. In total, 50% of the patients in the survey had no planned NDMR. In 8% (4) of patients, there was a significant ocular deviation. One of these four patients had total intravenous anesthesia (TIVA), while the other three were ventilated. None of them had taken NDMRs, or non-depolarizing muscle relaxants. In one case, the anaesthesia was deepened, and in two other cases, NDMR was administered as a remedy for the deviation. The prevalence of this condition was 18% in patients not receiving NDMR.The objective refraction values showed that myopia manifested as a result of general anesthesia. Under the same circumstances, corneal refractive values flatten, indicating that the primary cause of myopia was ciliary muscle contraction. We hypothesize that this alteration resulted from ciliary muscle contraction and parasympathetic dominance during general anesthesia.