CMV retinitis in China and SE Asia: the way forward

Selection of pre-trained weights for transfer learning in automated cytomegalovirus retinitis classification

Cytomegalovirus retinitis (CMVR) is a significant cause of vision loss. Regular screening is crucial but challenging in resource-limited settings. A convolutional neural network is a state-of-the-art deep learning technique to generate automatic diagnoses from retinal images. However, there are limited numbers of CMVR images to train the model properly. Transfer learning (TL) is a strategy to train a model with a scarce dataset. This study explores the efficacy of TL with different pre-trained weights for automated CMVR classification using retinal images. We utilised a dataset of 955 retinal images (524 CMVR and 431 normal) from Siriraj Hospital, Mahidol University, collected between 2005 and 2015. Images were processed using Kowa VX-10i or VX-20 fundus cameras and augmented for training. We employed DenseNet121 as a backbone model, comparing the performance of TL with weights pre-trained on ImageNet, APTOS2019, and CheXNet datasets. The models were evaluated based on accuracy, loss, and other performance metrics, with the depth of fine-tuning varied across different pre-trained weights. The study found that TL significantly enhances model performance in CMVR classification. The best results were achieved with weights sequentially transferred from ImageNet to APTOS2019 dataset before application to our CMVR dataset. This approach yielded the highest mean accuracy (0.99) and lowest mean loss (0.04), outperforming other methods. The class activation heatmaps provided insights into the model's decision-making process. The model with APTOS2019 pre-trained weights offered the best explanation and highlighted the pathologic lesions resembling human interpretation. Our findings demonstrate the potential of sequential TL in improving the accuracy and efficiency of CMVR diagnosis, particularly in settings with limited data availability. They highlight the importance of domain-specific pre-training in medical image classification. This approach streamlines the diagnostic process and paves the way for broader applications in automated medical image analysis, offering a scalable solution for early disease detection.

Human cytomegalovirus infection among treatment-naive HIV-1 infected patients in Ethiopia

Subclinical human cytomegalovirus (HCMV) replication is associated with immune dysfunction in immuno-suppressed antiretroviral therapy (ART) naive HIV infected individuals. No data is documented in Ethiopia so far concerning HCMV co-infection among HIV infected individuals. Hence, this study was aimed at generating data regarding the prevalence of active HCMV infection among treatment-naive HIV-infected individuals from Ethiopia. For this purpose, we enrolled 97 treatment-naive HIV infected study subjects in Addis Ababa from June to December 2018. ELISA and conventional PCR were performed consecutively to detect HCMV specific IgM antibody and HCMV DNA respectively. Of the 97 study subjects, 12 (12.4%) were positive for anti-CMV IgM antibodies but were not confirmed by PCR. With regard to the PCR positivity, 4/97 (4.1%) samples were positive for HCMV DNA. No statically significant associations were found between the dependent and independent variables. The presence of HCMV DNA in the current study highlights the need for a routine laboratory diagnosis for preventing HCMV disease among HIV-infected individuals early. Besides, the use of anti-CMV therapy for these CMV viremic individuals is also recommended as this can reduce the burden of CMV complications and consecutively prolonging the life of HIV infected individuals.

Clinical Features and CD4+ T Cells Count in AIDS Patients with CMV Retinitis: Correlation with Mortality

PURPOSE

To explore the all-cause mortality in patients with acquired immune deficiency syndrome (AIDS) and Cytomegalovirus (CMV) retinitis.

METHODS

A retrospective cohort study of patients with CMV retinitis (CMVR) presented to a tertiary referral center in Singapore from January 1, 2004, through December 31, 2015.

RESULTS

A total of 144 patients were studied (87 survived, 11 lost to follow up, 46 died). Patients with bilateral CMVR and six-month follow up CD4 + T cell count < 50 cells/mm³ have shorter time to mortality, compared to patients with CD4 + T cell count > 50 cells/mm³ (p < .001) and unilateral disease (p = .043). Baseline CD4 + T cell count, size and zone of initial primary retinitis lesions, recurrences of retinitis, and timing of combined antiretroviral therapy (cART) are not significantly associated with mortality.

CONCLUSION

Bilateral ocular involvement and lack of immune recovery in patients with AIDS and CMVR are associated with shorter survival time.

Visual acuity outcomes in cytomegalovirus retinitis: early versus late diagnosis

Aims

To determine if early dilated fundus examination for cytomegalovirus (CMV) retinitis leads to better visual outcomes in areas with limited HIV care, where patients may have long-standing retinitis before they are diagnosed with HIV.

Methods

Twenty-four eyes of 17 patients with CMV retinitis who were seen at an urban HIV clinic in Chiang Mai, Thailand, were included in this retrospective cohort study. Participants were divided into two groups based on the amount of time from the first documented CD4 count below 100 cells/mm3 to the first eye examination for CMV retinitis. Average visual acuity in each group was calculated at the time CMV retinitis was first detected, and then at 3, 6 and 12 months after diagnosis.

Results

The group of patients who received an eye examination within approximately 4 months of the initial low CD4 count measurement had better baseline visual acuity (median 20/30,IQR 20/20 to 20/60) compared with patients who presented later (median 20/80, 20/60 to hand motion); p=0.03). Visual acuity did not change significantly during the 12-month study period in either the early group (p=0.69) or late group (p=0.17).

Conclusion

In this study, patients who were examined sooner after a low CD4 count had better vision than patients who were examined later. Routine early screening of patients with CD4 counts under below 100 cells/mm3 may detect earlier disease and prevent vision loss.

Risk factors for CMV retinitis among individuals with HIV and low CD4 count in northern Thailand: importance of access to healthcare

AIM

To determine if poor access to healthcare is associated with increased cytomegalovirus (CMV) retinitis risk among patients with HIV with CD4 counts of <100 cells/μL screened in a resource-limited setting.

METHODS

This is a prospective cross-sectional study. Patients with known HIV and a CD4 count of <100 cells/μL attending an HIV clinic in Chiang Mai, Thailand, completed a standardised questionnaire and underwent dilated fundus examination. Participants without CMV retinitis were invited for repeated examinations every 3 months until their CD4 count exceeded 100 cells/μL. The relationship between various potential risk factors and CMV retinitis was assessed with logistic regression.

RESULTS

103 study participants were enrolled. At enrolment, the mean age was 37.5 (95% CI 35.7 to 39.2) years, 61.2% (95% CI 51.6% to 70.7%) were male and the mean CD4 count was 29.5 (95% CI 25.9 to 33.1) cells/μL. 21 eyes from 16 (15.5%) participants were diagnosed with CMV retinitis. In multivariate analyses, CMV retinitis was significantly associated with lower CD4 count (OR 1.42 per 10-cell decrement, 95%CI 1.05 to 1.93), longer travel time to clinic (OR 3.85 for those with >30-min travel time, 95% CI 1.08 to 13.8) and lower income (OR 1.22 per US$50 less income, 95% CI 1.02 to 1.47).

CONCLUSIONS

CD4 count, low income and longer travel time to clinic were significant risk factors for CMV retinitis among patients with HIV in a resource-limited setting. These results suggest that reducing blindness from CMV retinitis should focus on increasing accessibility of screening examinations to poor and hard-to-reach patients.

Telemedicine screening for cytomegalovirus retinitis at the point of care for human immunodeficiency virus infection

IMPORTANCE

Cytomegalovirus (CMV) retinitis is a leading cause of blindness in many developing countries, likely the result of inadequate screening. Telemedicine screening for CMV retinitis instituted at the point of care for human immunodeficiency virus (HIV) infection may allow for earlier detection.

OBJECTIVES

To determine the diagnostic accuracy of retinal photography in detecting CMV retinitis at the point of HIV care and to characterize the clinical manifestations of CMV retinitis detected through the screening program.

DESIGN, SETTING, AND PARTICIPANTS

We enrolled 103 participants from a population of 258 patients with HIV and a CD4 level of less than 100/μL treated at an HIV clinic in Thailand from June 2010 through June 2012. We captured mosaic fundus photographs through a dilated pupil using a digital fundus camera. An experienced on-site ophthalmologist masked to the results of the fundus images subsequently examined each eye with indirect ophthalmoscopy and recorded the clinical findings on a standardized form. Three remote graders evaluated each image for CMV retinitis.

INTERVENTION

Fundus photography and indirect ophthalmoscopy.

MAIN OUTCOMES AND MEASURES

Sensitivity and specificity of telemedicine relative to indirect ophthalmoscopy for diagnosis of CMV retinitis and clinical features of CMV retinitis lesions.

RESULTS

Sixteen patients (15.5%) were diagnosed as having CMV retinitis, of whom 5 (31%) had bilateral disease. Of the 21 eyes (10.2%) with CMV retinitis, 7 (33%) had visual symptoms. Retinitis lesions occupied less than 10% of the total retinal surface area in 13 of 21 eyes (62%) and did not involve the posterior pole (ie, zone 1) in 15 of 21 eyes (71%). Mean logMAR visual acuity in affected eyes was 0.41 (95% CI, 0.11-0.71; Snellen equivalent, 20/50 [95% CI, 20/25-20/100]). The mean sensitivity for the 3 remote graders in detecting CMV retinitis on fundus photography was 30.2% (95% CI, 10.5%-52.4%), and mean specificity was 99.1% (95% CI, 97.8%-100.0%). The CMV retinitis lesions missed by the remote graders (false-negative findings) were more likely to be small (P = .001) and located in the peripheral retina (P = .04).

CONCLUSIONS AND RELEVANCE

Patients undergoing screening at a clinic for HIV treatment had less extensive retinitis than patients in recent reports from an ophthalmology clinic. Retinal photography with the camera used in this study was not highly sensitive in detecting CMV retinitis but may identify disease with an immediate threat to vision. Improved accuracy will require a camera that can more easily image the peripheral retina.

Prevalence and predictors of cytomegalovirus retinitis in HIV-infected patients with low CD4 lymphocyte counts in Vietnam

We describe the results of a study to determine the prevalence and characteristics of cytomegalovirus (CMV) retinitis among HIV-infected patients in Vietnam. We conducted a cross-sectional prospective study of patients with CD4 lymphocyte count ≤100 cells/mm(3)recruited from public HIV clinics. The diagnosis was made by a trained ophthalmologist using slit lamp biomicroscopy and corroborated on fundus photography. A total of 201 patients were screened. The median age was 32 years, 77% were men, median CD4 count was 47 cells/mm(3), and 62% were on antiretroviral treatment. Prevalence of CMV retinitis was 7% (14/201, 95% CI 4-11%). CMV retinitis was not associated with age, gender, injection drug use, CD4 count, WHO clinical stage, or antiretroviral treatment status. Blurring of vision and reduced visual acuity <20/40 were associated with CMV retinitis, but only 29% of patients with the diagnosis reported blurry vision and only 64% had abnormal vision. On multivariate analysis, the sole predictor for CMV retinitis was decreased visual acuity (OR 22.8,p < 0.001). In Ho Chi Minh City, CMV retinitis was found in 7% of HIV-infected patients with low CD4. HIV-infected patients with a CD4 count <100/mm(3)or who develop blurring of vision in Vietnam should be screened for CMV retinitis.