Introduction
Asteroid hyalosis is a common degenerative process in which calcium pyrophosphate particles collect within the vitreous gel. It is seen clinically as numerous tiny round yellow-white opacities of various size and density. An autopsy study1 of 10801 eyes found an incidence of 1.96%;with male/female ratio of 2:1. Asteroid hyalosis is unilateral in greater than 75% of cases.
Asteroid bodies are associated with the vireous gel and move with vitreous displacement during eye movement, thereby suggesting a relationship with age related collagen fibril degeneration. However, PVD either complete or partial occurs less frequently in individuals with asteroid hyalosis than in age-matched controls and this finding does not support age related degeneration as a cause. The prevalence of asteroid hyalosis increases with age and affects 3% of those aged 75-86 years. OCT and ultrasonography show high reflectivity foci.
Some reports have suggested an association2, 3, 4, 5 between asteroid hyalosis and diabtes mellitus whereas other investigations found no such association.6, 7, 8 Asteroid hyalosis appears to be associated with certain pigmentary retinal degenerations although it is not known whether this is related to the presence of diabetes in these patients.
Yu and Blumenthal9 proposed that asteroid hyalosis results from aging collagen whereas other studies have suggested that asteroid formation is preceded by depolymerization of hyaluronon.
The most interesting aspect of asteroid hyalosis is marked absence of patient complaints and symptoms. Although it can be difficult in some cases to examine and image the fundus, these patients often experience no visual disturbances whereas patients with PVD can be markedly symptomatic. It is hypothesized that the explaination is related to the smooth surfaces of asteroid bodies that may not scatter light in as disturbing a fashion as irregular surfaces of the collagen fibrils of the vitreous body.
Materials and Methods
The study was done in the Department of Ophthalmology, MLB Medical College, Jhansi from February 2019-december 2019. A total of 80 patients presenting to the OPD who were diagnosed with asteroid hyalosis and fitted the inclusion and exclusion criteria were taken for the study. It was performed under the Helsinki Declaration of 1975, as revised in 2000. An informed consent of the patients was taken and necessary permission was obatained from the Ethical and Research Committee for the study.
The 80 patients diagnosed with asteroid hyalosis were divided into two groups-
Group A- diabetic (those with random blood sugar of 200mg/dl or higher or HbA1c higher than 6.5%).
Group B- non-diabetic (those with random blood sugar less than 200 mg/dl or HbA1c less than 6.5%).
All the patients of Group A and Group B will undergo complete ophthalmic examination, which includes best corrected visual acuity, slit lamp anterior segment examination, slit lamp biomicroscopy (+90D)/ indirect ophthalmoscopy for posterior segment examination. Detailed history of all patients was taken regarding duration of diabetes and treatment. Random blood sugar and HbA1c levels were recorded.
Inclusion criteria
All patients presenting to the OPD of the Department of Ophthalmology, MLB Medical College, Jhansi between February 2019- December 2019 with the diagnosis of asteroid hyalosis.
Exclusion criteria
Patients with Diabetes Mellitus with hypertension, thyroid disorder and other systemic diseases.
Patients having other retinal or vitreous disorders.
Patients having corneal pathology and any other ocular abnormalities like pterygium, entropionj, trichiasis.
Patients who have undergone previous ocular surgeries.
Mentally or physically unfit patients.
Statistical analysis
All analyses were performed using statistical software Graph pad. All means were expressed as mean ± standard deviation. Differences of means were analyzed using the t-test where appropriate and forward stepwise binary logistic regression was implemented for analysis of the variables: random blood sugar and HbA1c levels in association with the development of asteroid hyalosis. The critical value of significance was set at P< 0.05 for all tests.
Results
The 80 patients diagnosed with asteroid hyalosis were divided into two groups; Group A with diabetes and Group B without diabetes. In Group A there were 68.42% males (13) and 31.58% females (6) and in Group B there were 70.50% males (43) and 29.50% females (18).
In group A 63.16% (12) patients showed unilateral eye involvement and 36.84% (7) patients showed bilateral eye involvement while in group B 80.33% (49) patients showed unilateral eye involvement and 19.67% (12) patients showed bilateral involvement.
Group A had 19 patients therefore 23.75% of patients with asteroid hyalosis were diabetic while Group B had 61 patients therefore 76.25% of patients with asteroid hyalosis were non-diabetic.
The mean random blood sugar was found to be 239.26±38.37 mg/dl in group A while in group B it was found to be 132.31±26.26 mg/dl. The p-value was found to be <0.0001 which was extremely statistically significant.
The mean HbA1c levels was found to be 8.4±1.3 % in group A whereas in group B it was 5.4±0.6%.
The p-value was found to be <0.0001 which was extremely statistically significant. The median age of presentation was found to be 40-75 years.
Table 1
Sex distribution of patients in Group A and Group B
| Group | Sex | Number of patients | Percentage |
| Group A | Males | 13 | 68.42% |
| Females | 6 | 31.58 | |
| Group B | Males | 43 | 70.50% |
| Females | 18 | 29.50% |
Table 2
Eye involvement in Group A and Group B
| Group | Eye involved | Number of patients | Percentage |
| Group A | Unilateral | 12 | 63.16% |
| Bilateral | 7 | 36.84% | |
| Group B | Unilateral | 49 | 80.33% |
| Bilateral | 12 | 19.67% |
Discussion
There have been quite a few studies to determine the association between diabetes mellitus and asteroid hyalosis and till date the association between the two remains debatable. While in some studies the relation between the two has been clearly established, others have completely ruled out the possibility of any correlation.
In our study out of 80 patients who were diagnosed with asteroid hyalosis 19(23.75%) had established diabetes mellitus. The mean random blood sugar was found to be 239.26±38.37 mg/dl in group A while in group B it was found to be 132.31±26.26 mg/dl. The p-value was found to be <0.0001 which was extremely statistically significant. The mean HbA1c levels was found to be 8.4±1.3% in group A whereas in group B it was 5.4±0.6%. The p-value was found to be <0.0001 which was extremely statistically significant. Zinn10 found 27% patients with asteroid hyalosis were diabetic while Bergren11 found that 29% of asteroid hyalosis patients were diabetic. Jones12 has also documented a patient with acquired asteroid hyalosis in a case of early diagnosed diabetes mellitus which strongly supports a association between the two conditions The Blue Mountains Eye Study13 on the other hand, failed to establish a significant association between asteroid hyalosis and diabetes as well as other systemic conditions like heart disease, higher body mass index, a history of gout and of higher levels of alcohol consumption.
Bilateral asteroid hyalosis was found in 23.75% of our patients. Moss14 in his study found approximately 9% bilateral cases of asteroid hyalosis whereas according to Zinn10 it was 25%. Therefore it is quite clear that asteroid hyalosis is mostly unilateral. The bilateral cases of asteroid hyalosis are mostly related to systemic diseases like diabetes, the rationale being that both the eyes are equally exposed to a particular systemic condition (like hyperglycemia in case of diabetes mellitus). In our study also the diabetes group A has 36.84% bilateral involvement as compared to 19.67% bilateral involvement in the non diabetic group. This fact has also been confirmed by the UCLA autopsy study,1 which observed a statistical association between diabetes and bilateral AH before adjusting the data for age and sex.
In our study asteroid hyalosis was found to be higher in males (68.42% in group A 70.50% in group B. Various other studies have also shown higher incidence in males.6, 7, 13, 15, 16, 17
Conclusion
Diabetes mellitus emcompasses within itself a wide range of multi systemic diseases. Almost all body organs are affected in some way or the other by this disease. Asteroid hyalosis is a benign condition in which the eye develops yellow white opacities within the vitreous. The association between asteroid hyalosis and diabetes mellitus has been a debatable topic in ophthalmology. Though it has not been clearly established yet if the two are related or not but the evidence is enough to consider diabetes as a risk factor for asteroid hyalosis especially in cases of bilateral asteroid hyalosis. It is therefore advisable that patients of asteroid hyalosis should be screened for diabetes mellitus.
