The preoccupation of the medical community in the management of the COVID-19 crisis has resulted in the neglect of non-COVID-19 medical conditions. The limitation in the number of surgical cases to maintain the social distancing guidelines and deferred operations have added to the surgical backlog considerably. To reverse this downturn the world is struggling to bounce back by adopting the “new normal.” Resumption of health care services poses a challenge due to the safety concerns for the medical and paramedical personnel. More importantly, in presymptomatic cases, the signs and symptoms of COVID-19 may manifest in the postoperative period, culminating in adverse patient outcomes.
The patients undergoing surgery may be presymptomatic or asymptomatic COVID-19 cases. The reported transmission efficiency of an asymptomatic carrier is one-third of that of symptomatic cases. Real-time reverse transcriptase–polymerase chain reaction (RT-PCR) of the nasopharyngeal swab is thus recommended prior to intervention, especially in procedures involving aerosol generation. However, the probability of detection of SARS-CoV-2 nucleotide by RT-PCR peaks on day 3 of symptoms, and the sensitivity in asymptomatic cases is not known.
To evaluate the rationale for preoperative COVID testing, we performed a retrospective analysis of RT-PCR of nasopharyngeal samples of patients posted for elective ophthalmic surgery from July 26, 2020, to August 25, 2020, at Guru Nanak Eye Center, New Delhi. Institutional ethics committee clearance was obtained for data analysis.
Due to the diversion of anesthetists and reservation of hospital beds for management of critically ill COVID-19 patients, all ophthalmic surgeries were performed under local anesthesia on a daycare basis. The patients with signs or symptoms/positive lab-confirmed COVID-19 cases in the prior 2 weeks, uncontrolled diabetes, hypertension, heart disease, pregnancy, chronic lung/liver disease, or immunocompromised status were not included. All patients planned for elective ophthalmic surgery underwent RT-PCR for SARS COV-2 from the nasopharyngeal swab a day prior to the procedure. The RT-PCR testing was performed at the advanced virology laboratory, Maulana Azad Medical College, New Delhi, using an Indian Council of Medical Research approved kit.
In the patients with a positive nasopharyngeal swab, cycle threshold (Ct) values of E gene, ORF1b/N gene, and RdRp gene were determined from the amplification curves. [Fig. 1a-c] Ct value of the E gene was used to study the viral load. These patients were also contacted telephonically to ascertain the development of signs and symptoms related to COVID-19 until 3 weeks after the test.
In the 1-month period, 355 asymptomatic patients planned for cataract, squint, lid, lacrimal, and retinal surgery underwent RT-PCR testing. Thirty cases, with ages ranging from 18 years to 64 years and male:female ratio 8:7 tested positive [Table 1]. None of these patients developed COVID-19 symptoms in the 21 days after the test. The average Ct value of the E gene of the positive cases was 27.63 and in nine cases being <24 (15-22).
Asymptomatic COVID-19 cases are common in young and middle-aged population, the median age being 32.5 years and 49 years, respectively. The median age in our study also was 36.5 years.
The reported population prevalence of active COVID-19 cases in Delhi in the study period was 10.47%. This included both symptomatic as well as asymptomatic laboratory-confirmed cases. The incidence of asymptomatic COVID-19 infections has been reported to vary from 1.6% to 56.5%. We observed RT-PCR positivity of 8.4% in the nasopharyngeal samples of preoperative ophthalmic surgery cases. The absence of systemic symptoms in these patients could be attributed to the innate immune response. The median period reported for an asymptomatic patient to become negative for viral nucleic acid is 9.5 days and the longest is up to 21 days. All the positive patients were informed, quarantined for 14 days and the surgeries were deferred.
The major drawback of RT-PCR is its inability to demonstrate infectivity. The viral nucleic acid positivity, merely indicates that the viral load in a sample reaches a certain limit. Definitive proof of the potential for viral transmission can be obtained by in-vitro infectiousness on cell lines, but is labor-intensive and requires containment level three facilities. Bullard et al. demonstrated that infectivity as evidenced by the growth in cell culture was significantly reduced when RT-PCR values were >24 and the odds ratio for infectivity decreased by 32% for every 1 unit increase in Ct value. In our study, nine cases (30% of the positive samples; 2.53% of total tested samples) had Ct values <24, which could have been infective. Their age groups varied from 18 to 51 years. The remaining 19 cases though positive, had Ct value more than 24, chances of infectivity being less. The infectivity has been observed to decrease when the duration of symptoms is more than 8 days. In asymptomatic cases, it is not possible to predict the infectivity in terms of duration of illness as the time of exposure is not known. Though RT-PCR is a qualitative test, the Ct value can thus serve as a guide to determine the infectiousness of the patient.
An asymptomatic apparently healthy patient undergoing elective ophthalmic surgery could be a source of COVID-19 transmission to the health care workers. With the ease of availability and emphasis on more testing, RT-PCR for COVID should form a part of the standard operating protocol, prior to all ophthalmic procedures. We hope that our experience in this evolving public health challenge would help in strategic planning to enable the provision of safe surgical care.
1.1 About the authors
Prof. Ruchi Goel is serving at the Guru Nanak Eye Centre, Maulana Azad Medical College, New Delhi since 2006. She is a volunteer faculty at ORBIS International. She has authored the book "Manual of Oculoplasty" in 2019 and has co-authored "Manual of SICS" with focus on difficult situations and complications in 2011. She has contributed over 100 articles in journals, book chapters and three CME series by AIOS. She is the recipient of Dr. V.P. Chadha Memorial University Gold Medal (Delhi University), Smt. Rukmani Gopala Krishnan Memorial Gold Medal (Delhi University), AIOS-APAO-Honavar Award for the Best Paper in the lacrimal session, AIOS-IJO Silver Award and the Outstanding Paper by the International College of Surgeons.
Prof. Ritu Arora, Director, Guru Nanak Eye Center, New Delhi is a graduate and post-graduate from AIIMS, New Delhi. She did her WHO fellowship at Wills Eye Hospital, and Toronto Western Hospital in 1996 and endothelial keratoplasty training at Oregon under Dr Mark Terry. Her areas of interest are cornea, refractive surgery, ocular surface and eye banking. She has 95 publications in national and international peer reviewed journals and has contributed 12 book chapters. She has over 300 presentations in national and international forums. She has conducted 8 clinical trials as the principal investigator. She is the recipient of the AAO Achievement Award 2010, Noel Moniz Oration 2016 and ISCKRS Appreciation Award 2017.
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