Corneal biomechanical alterations in patients with chronic ocular Graft Versus-Host Disease

Recent advances in ocular graft-versus-host disease

Ocular graft-versus-host-disease (GVHD) remains a significant clinical complication after allogeneic hematopoietic stem cell transplantation. Impaired visual function, pain, and other symptoms severely affect affected individuals' quality of life. However, the diagnosis of and therapy for ocular GVHD involve a multidisciplinary approach and remain challenging for both hematologists and ophthalmologists, as there are no unified international criteria. Through an exploration of the complex pathogenesis of ocular GVHD, this review comprehensively summarizes the pathogenic mechanism, related tear biomarkers, and clinical characteristics of this disease. Novel therapies based on the mechanisms are also discussed to provide insights into the ocular GVHD treatment.

Clinical Manifestation of Infectious Keratitis in Ocular Graft Versus Host Disease

Purpose: We evaluated the clinical manifestations of, and risk factors for, infectious keratitis in patients with ocular graft-versus-host disease (GVHD).Methods: A total of 11 patients who developed infectious keratitis after a diagnosis of ocular GVHD between January 2015 and December 2020, and 36 who did not (the control group), were included in this retrospective study. We recorded sex, age, any underlying disease, any other organ affected by systemic GVHD, systemic immunosuppressant use, follow-up duration, clinical manifestations, the severity of ocular GVHD prior to infection, the size of the epithelial defect, the depth of infiltration, hypopyon status, and the results of microbiological tests. Systemic and ocular indices (including systemic GVHD status) were compared using the chi-squared test. Risk factors for infection were identified.Results: Of the corneal indices, the presence of corneal filaments, the extent of corneal neovascularization, and the number of corneal epithelial defects were significantly higher in the infected group (p = 0.023, p = 0.004, and p = 0.001, respectively). GVHD severity was also significantly higher in that group (p < 0.001). The presence of corneal filaments, corneal neovascularization, and corneal epithelial defects prior to infection correlated significantly with the risk of infection (p = 0.046, p = 0.010, and p = 0.003, respectively). Multivariate analysis identified corneal epithelial defects as a significant risk factor for infection (p = 0.029).Conclusions: In patients with ocular GVHD, corneal epithelial defects, corneal neovascularization, and corneal filaments prior to infection were associated with the development of infection. In particular, corneal epithelial defects before infection was a significant risk factor for infection.

Corneal biomechanical properties in patients with kidney transplant

PURPOSE

The purpose of the study was to evaluate the corneal biomechanical properties in patients post kidney transplant and to compare them with healthy age-matched control.

MATERIALS AND METHODS

In this cross-sectional study, 68 patients with kidney transplant (study group) and 68 healthy individuals (control group) were analyzed with ocular response analyzer measurements. Only the right eye of each participant was assessed for corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOP_cc), and Goldmann-correlated intraocular pressure (IOP_g).

RESULTS

The mean CH in the study group was 9.70 ± 1.62 mmHg which was significantly lower than the control group with the mean CH of 10.60 ± 1.49 mmHg (P = 0.001). The mean IOP_cc was 18.17 ± 4.00 mmHg and 16.00 ± 3.94 mmHg in the study and control groups, respectively (P = 0.002). CRF and IOP_g were not significantly different between groups.

CONCLUSION

CH and IOP_ccare altered in kidney transplant patients.

Alteration of corneal biomechanical properties in patients with dry eye disease

Purpose

To evaluate the association between symptoms and signs of dry eye diseases (DED) with corneal biomechanical parameters.

Methods

This cross-sectional study enrolled 81 participants without history of ocular hypertension, glaucoma, keratoconus, corneal edema, contact lens use, diabetes, and ocular surgery. All participants were evaluated for symptoms and signs of DED using OSDI questionnaire, tear film break-up time (TBUT), conjunctival and corneal staining (NEI grading) and Schirmer test. Corneal biomechanical parameters were obtained using Corvis ST. Mixed-effects linear regression analysis was used to determine the association between symptoms and signs of DED with corneal biomechanical parameters. Difference in corneal biomechanical parameter between participants with low (Schirmer value ≤10 mm; LT group) and normal (Schirmer value >10mm; NT group) tear production was analyzed using ANCOVA test.

Results

The median OSDI scores, TBUT, conjunctival and corneal staining scores as well as Schirmer test were 13±16.5 (range; 0–77), 5.3±4.2 seconds (range; 1.3–11), 0±1 (range; 0–4), 0±2 (ranges; 0–9) and 16±14 mm (range; 0–45) respectively. Regression analysis adjusted with participants’ refraction, intraocular pressure, and central corneal thickness showed that OSDI had a negative association with highest concavity radius (P = 0.02). The association between DED signs and corneal biomechanical parameters were found between conjunctival staining scores with second applanation velocity (A2V, P = 0.04), corneal staining scores with second applanation length (A2L, P = 0.01), Schirmer test with first applanation time (A1T, P = 0.04) and first applanation velocity (P = 0.01). In subgroup analysis, there was no difference in corneal biomechanical parameters between participants with low and normal tear production (P>0.05). The associations were found between OSDI with time to highest concavity (P<0.01) and highest displacement of corneal apex (HC-DA, P = 0.04), conjunctival staining scores with A2L (P = 0.01) and A2V (P<0.01) in LT group, and Schirmer test with A1T (P = 0.02) and HC-DA (P = 0.03), corneal staining scores with A2L (P<0.01) in NT group.

Conclusions

According to in vivo observation with Corvis ST, patients with DED showed more compliant corneas. The increase in dry eye severity was associated with the worsening of corneal biomechanics in both patients with low and normal tear production.

Conjunctival Matrix Metalloproteinase-9 Clinical Assessment in Early Ocular Graft versus Host Disease

Purpose

Graft versus Host Disease (GVHD) typically affects the ocular surface, with a presentation resembling Dry Eye Disease (DED). Although the etiopathology is not completely known, the conjunctiva might be a key site of T-cell activation. The differential diagnosis might be tricky at early stages, because of the lack of dedicated clinical and laboratory tests. To meet these needs, we evaluated the suitability of ocular surface matrix metalloproteinase-9 (MMP-9) clinical test.

Methods

Consecutive GVHD patients, referred to IRCCS San Raffaele Scientific Institute, were recruited. DED patients served as controls. MMP-9 was tested through InflammaDry immunoassay kit in both groups; Ocular Surface Disease Index (OSDI) questionnaire, tear osmolarity, fluorescein Tear Break-up Time (TBUT), corneal and conjunctival staining, and Schirmer test I were also collected. Parametric and nonparametric statistical tests were used to analyze the intergroup differences; Receiver Operating Characteristics (ROC) curve analysis was carried out to perform sensitivity and specificity evaluations.

Results

Forty-five GVHD and 40 DED patients were included. MMP-9 expression was significantly higher in GVHD group than in DED (84.4% vs 33%, p ≤ 0.001). Corneal and conjunctival staining scores resulted worse in GVHD than in DED (0.95 ± 1.16 vs 0.40 ± 0.63, p=0.02; 0.77 ± 0.42 vs 0.40 ± 0.49, p=0.0005, respectively). No significant differences regarded the other collected parameters. GVHD group was characterized by positive correlations between MMP-9 and conjunctival staining (rho = 0.55, p=0.0002) and between MMP-9 and OSDI (rho = 0.3, p=0.01); a faint inverse correlation was found between MMP-9 and Schirmer test (rho = −0.25, p=0.04).

Conclusion

MMP-9 has a role in physiologic cellular remodeling; when a proinflammatory stimulus occurs, MMP-9 molecules are overreleased in the extracellular matrix. The positive expression of MMP-9 in GVHD may be interpreted as the consequence of a T-cell aggression against self-antigens and may be considered a reliable biomarker to detect ocular surface inflammation in GVHD, even in early stages of the disease.

Meibomian Gland Dysfunction in Ocular Graft vs. Host Disease: A Need for Pre-Clinical Models and Deeper Insights

Despite decades of experience with hematopoietic stem cell transplantation, we are still faced with the delicate equipoise of achieving stable ocular health post-transplantation. This is because ocular graft-versus-host disease (oGvHD) following hematopoietic stem cell transplantation frequently occurs (≥50%) among transplant patients. To date, our understanding of the pathophysiology of oGvHD especially the involvement of the meibomian gland is still limited as a result of a lack of suitable preclinical models among other. Herein, the current state of the etiology and, pathophysiology of oGvHD based on existing pre-clinical models are reviewed. The need for additional pre-clinical models and knowledge about the involvement of the meibomian glands in oGvHD are emphasized.

In vitro validation of the tear matrix metalloproteinase 9 in-situ immunoassay

We aimed to validate a tear MMP-9 in-situ immunoassay (InflammaDry) and to identify factors that could affect results or interpretation. Three factors were examined: sample concentration, volume, and time. Recombinant human (rh) MMP-9 (10 or 20 μl; 0, 12.5, 25, 50, 100, 200, 500, and 1,000 ng/ml) was applied to the kit and the detection limit and assay reproducibility were examined. At a rhMMP-9 volume of 10 μl (≥ 50 ng/ml), all positive results were identified by densitometry at 10 and 20 min; however, after 20 min, more than half of the nine ophthalmologists interpreted a positive result. At a rhMMP-9 volume of 20 μl (≥ 25 ng/ml), ophthalmologists and densitometry identified almost all test lines at 10 and 20 min. At 10 μl, densitometry showed a linear dose–response pattern. At 20 μl, densitometry showed a linear dose–response pattern at concentrations up to 500 ng/ml; however, full saturation was achieved at concentrations ≥ 500 ng/ml. When the same amount of rhMMP-9 was applied, the density result increased significantly upon doubling of the solvent volume (i.e., by adding the same volume of PBS to a sample). InflammaDry showed a high inter- and intra-assay coefficient of variation at 10 min (28.4% and 24.7%, respectively). The results of the MMP-9 in-situ immunoassay varied significantly depending on sample volume. Therefore, when interpreting the results, careful attention must be paid to tear volume.

Corneal Biomechanical Response Alteration After Scleral Buckling Surgery for Rhegmatogenous Retinal Detachment

PURPOSE

To compare the corneal biomechanics of eyes that underwent scleral buckle (SB) for rhegmatogenous retinal detachment (RRD) with those of fellow eyes (fellow eyes) and to further investigate the effects of SB on intraocular pressure (IOP) values.

DESIGN

Retrospective, fellow-eye matched cohort study.

METHODS

A total of 18 consecutive patients (11 males and 7 females) treated with SB for RRD in 1 eye were enrolled. Goldmann applanation tonometry was used to measure IOP. Biomechanical properties of the cornea were investigated by using the Ocular Response Analyzer (ORA) (Reichert Instruments) for the calculation of corneal resistant factor (CRF), corneal hysteresis, Goldmann-correlated IOP, and corneal-compensated IOP. Customized software was used for analysis of the ORA infrared and pressure signals, and a significance threshold was set to a P value of .05.

RESULTS

Operated eyes (OEs) showed significantly lower values of corneal hysteresis and CRF than fellow eyes (9.0 ± 1.8 vs 10.1 ± 1.8 mm Hg, respectively; P < .001; 10.0 ± 2.2 vs 10.9 ± 2.2 mm Hg; P < .001). GAT was significantly lower than corneal-compensated IOP in OEs (18.1 ± 4.9 vs 19.8 ± 4.8 mm Hg, respectively; P = .022) but not in fellow eyes. The second applanation event (A2) took place earlier in time, and the cornea was moving faster during A2 in the OEs than in the fellow eyes.

CONCLUSIONS

SB for the treatment of RRD affects corneal biomechanical response, likely due to a less compliant sclera that limits corneal motion and reduces energy dissipation, reflected in a lower corneal hysteresis. This has potentially meaningful clinical implications as the accuracy of the measurement of IOP values may be affected in these eyes.

Longitudinal Corneal Endothelial Cell Changes in Patients Undergoing Hematopoietic Stem Cell Transplantation

PURPOSE

To evaluate longitudinally corneal endothelial cell changes in patients undergoing hematopoietic stem cell transplantation (HSCT) and to further investigate possible correlations with hematological and ocular characteristics.

METHODS

Prospective observational study conducted at a single center. All patients underwent a comprehensive ophthalmological examination, before and after HSCT, including slitlamp examination, Schirmer test, tear breakup time, ocular surface staining, specular microscopy of corneal endothelium, and Ocular Surface Disease Index questionnaire.

RESULTS

Twenty-five patients undergoing HSCT and 25 age- and sex-matched controls were included. At baseline, hematological patients showed significantly lower values of endothelial cell density (ECD) compared with those of controls (2514.5 ± 390.2 vs. 2723.7 ± 298.0 cells/mm, P = 0.038). After HSCT, ocular surface disease index score significantly increased (P = 0.020) and tear breakup time significantly decreased (P = 0.036). Conversely, no significant changes were found in Schirmer test and corneal fluorescein staining (always P > 0.05). Eight patients (32%) developed ocular graft-versus-host disease (GVHD). ECD values significantly decreased after HSCT (from 2514.5 ± 390.2 to 2409.5 ± 330.9 cells/mm, P = 0.009). The decrease in ECD values after HSCT was more pronounced in patients with ocular GVHD compared with those without (231.1 ± 188.8 vs. 45.6 ± 156.5, P = 0.016). No significant correlations between the changes in ECD and hematological and ocular characteristics were found (always P > 0.05).

CONCLUSIONS

Hematological patients showed a lower endothelial cell count already before HSCT, compared with controls. After HSCT, the endothelial cell count further significantly decreased, particularly in patients who developed ocular GVHD.