Introduction

Graft-versus-host disease (GVHD) is a potentially life-threatening multiorgan systemic disease affecting patients treated with hematopoietic stem cell transplantation (SCT). GVHD is characterized by immune dysregulation and tissue inflammation with single- or multisystem involvement resulting in tissue fibrosis and organ dysfunction. Characteristic diagnostic features involving skin, mouth, gastrointestinal (GI) tract, lung, fascia, genitalia, eyes, nails, scalp, or hair are seen. Chronic GVHD (cGVHD) is a complex immune-mediated disorder that can target multiple organs, usually manifesting in the first year after HSCT and may occur in up to 30%–70% of the patients undergoing HSCT. Ocular GVHD (oGVHD), the most common long-term complication, affects 40%–60% of patients treated with allo-HSCT. Typically, oGVHD involves ocular surface, including the cornea, conjunctiva, lacrimal glands, meibomian glands, and eyelids. ^, Risk factors for oGVHD include male recipients of female donors skin, ^, oral mucosa, ^, liver, or GI tract involvement during acute or chronic stages of GVHD and lung involvement in cGVHD. Preexisting diabetes, recipients of transplants from Epstein–Barr Virus–positive donors, Asian and other ethnicities compared to Caucasian ethnicity were more likely to develop oGVHD.

Definition of OGVHD Diagnostic Criteria

As of now there are no molecular biomarkers that are pathognomonic or diagnostic for oGVHD, therefore the classifications are based on clinical tests. There are two widely acknowledged diagnostic classification criteria for oGVHD. The first one is the 2014 National Institute of Health Consensus conference (NIH) criteria. According to the NIH classification criteria, the diagnosis of chronic GVHD requires at least one diagnostic manifestation or one distinctive manifestation confirmed by biopsy or testing of the same or other involved organ. “Diagnostic” manifestations sufficient by themselves to establish the diagnosis of chronic GVHD may be found in the skin, mouth, GI tract, lung, fascia, and genitalia (for example, lichen planus or lichen sclerosis, poikiloderma, sclerosis, or esophageal webs). There are no diagnostic features of the nails, eyes, liver, or other organs. Distinctive manifestation of chronic GVHD include new onset of dry, “gritty” or painful eyes, cicatricial conjunctivitis, KCS, and confluent areas of punctate keratopathy. New ocular sicca documented by low Schirmer’s test with a mean value of ≤5 mm at 5 min or a new onset of KSC by slit lamp exam with mean Schirmer’s test values of 6–10 mm not due to other causes is sufficient for the diagnosis of ocular chronic GVHD. The International Chronic oGVHD consensus group (ICCGVHD) diagnostic criteria is based on scores derived from Ocular Surface Disease Index (OSDI), Schirmer’s test without anesthesia, corneal fluorescein staining (CFS), conjunctival injection and presence of systemic GVHD. The diagnostic categories included no oGVHD, probable oGVHD and definite oGVHD. While a comparative study of the newer NIH 2014 criteria and ICCGVHD criteria found moderate agreement between the two, ICCGVHD criteria was noted to be better at differentiating oGVHD patients from non-oGVHD DED (dry eye disease). Pre-allo-HSCT evaluation for DED is now widely recommended to help differentiate between preexisting dry eye and the new onset DED diagnosed as oGVHD post-allo-HSCT.

Clinical Features

Clinical Signs

Acute oGVHD commonly presents as pseudomembranous or hemorrhagic conjunctivitis. ^, A less severe form with conjunctival injection or chemosis may also be seen. Corneal signs include epithelial sloughing, ^, corneal epithelial keratitis, or filamentary keratitis which may be secondary to the conjunctival cicatrization due to the disease. Some patients may present with lagophthalmos. Ocular involvement in aGVHD is considered an extremely poor prognostic sign associated with a higher GVHD-related mortality. Chronic oGVHD primarily is a result of inflammatory and fibrotic changes in the ocular surface comprising the cornea, conjunctiva, lacrimal glands, meibomian glands, and eyelids ( Fig. 7.1 ). It should be noted that other factors such as conditioning regimens, irradiative therapy, and immunosuppression might also impact the clinical manifestations in addition to the GVHD disease process itself. Corneal signs due to the KCS syndrome include punctate keratitis, epithelial erosions, and epithelial defects ( Fig. 7.2 ) which may progressively worsen to keratinization, stromal thinning, melt, and perforation. Recurrent corneal perforation, sometimes bilaterally, is not uncommon with calcareous degeneration or lipid keratopathy being seen rarely. The progression from the stage of epithelial ulceration to perforation tends to be rapid and is often refractory to standard medical or surgical treatment modalities. Progressive ocular surface inflammation leads to corneal neovascularization, conjunctivalization, and less commonly limbal stem cell deficiency (LSCD), which will adversely affect visual acuity. Decreased corneal sensation tends to predispose development of neurotrophic ulceration. Conjunctival involvement is a distinctive aspect of chronic oGVHD, seen in about half of the chronic oGVHD and is a marker for severe systemic involvement of GVHD. ^, Less severe cases manifest as a conjunctival hyperemia or chronic conjunctivitis involving both palpebral and bulbar conjunctiva. Other less common features include cicatricial conjunctivitis with obliteration of fornices, cicatricial entropion, symblepharon, ankyloblepharon, and lagophthalmos, which could progress to conjunctival keratinization and punctal occlusion. ^{, ,} Conjunctival subepithelial fibrosis seen as fine white lines under intact conjunctival epithelium are indicative of a past insult. Pseudomembranous and serosanguineous conjunctivitis are less frequently seen forms of conjunctival involvement which though more characteristic of acute oGVHD, have been seen in chronic oGVHD too. Subtarsal fibrosis in upper tarsus noted in 40% chronic oGVHD cases along with worsening of ocular surface epitheliopathy in these patients was suggested to be of diagnostic value in oGVHD. Decreased conjunctival goblet cell density and increased squamous cell metaplasia and surface keratinization of the ocular surface have also been noted. Superior limbal keratoconjunctivitis like inflammation has been reported as a manifestation of oGVHD, which can worsen to LSCD and corneal pannus formation. This has been attributed to soft tissue microtrauma from increased frictional forces compounded by tear mucin deficiency due to goblet cell loss. Meibomian glands are severely affected with rapid and aggressive destruction over time in chronic oGVHD resulting in unstable tear film aggravating the DED. T-cell–mediated damage to the MG epithelial cells is primarily responsible for the gland dysfunction with hyperkeratinization of duct epithelium and subepithelial stromal fibrosis contributing to obstructive Meibomian Gland Dysfunction (MGD) in chronic GVHD. The prevalence of MGD ranges about 47.8%–68.4% in oGVHD. ^, The MG loss and damage in oGVHD is often more severe than that seen in other DED such as Sjögren’s syndrome. Early detection and aggressive management can perhaps help in minimizing damage in oGVHD as few studies have shown some reversibility of MG damage in the initial stages. ^{, ,} Meibography revealed loss of about 80% MG function in oGVHD patients evaluated over a 1-year period with over 25% being refractory to treatment. Lid margin irregularity, vascular engorgement, plugging of MG, and displacement of mucocutaneous junction due to duct outlet obstruction is also seen. ^, In vivo confocal microscopy (IVCM) imaging has documented morphological changes like inflammatory cell infiltration, gland atrophy, and fibrosis. MG loss does seem to be more with increasing severity of oGVHD. Prevalence of posterior blepharitis associated with MGD has been reported in 47%–63% of chronic GVHD patients, with significant correlation with the severity of KCS symptoms. ^,

A1: Showing external eye image, the lid margin with telangiectasia. A2: Fornix shortening, subconjunctival fibrosis, and extensive redness. A3: Conjunctival subepithelial fibrosis (CSEF) in the upper lid. B1: Lissamine green staining showing severe corneal Superficial Punctate Keratitis (SPKs). B2: Severe conjunctival staining with lissamine green. B3: Superior bulbar staining (SLK type) with lissamine green. C1: Scleral lens that is commonly used for treating oGVHD. C2: A soft bandage contact lens used for treating oGVHD. C3: shows that the cornea and conjunctiva that is covered with contact lens does not stain with lissamine green dye, however conjunctival areas outside contact lens show severe staining.

(A) Persistent epithelial defect in oGVHD patient. (B) Inflammatory mucus cellular aggregates (MCA) sticking to the epithelial defect area. These MCA are composed of neutrophil extracellular traps (NETS) that contain bioactive molecules and cytokines that may cause cytotoxicity.

Lacrimal gland involvement is responsible for the tear aqueous deficiency in oGVHD with the resultant DED or KCS being the most characteristic feature in up to 69%–77% of oGVHD cases. Fibrosis and inflammation caused by stromal fibroblasts with T-cell infiltration, around the periductal area of lacrimal gland, leads to the destruction of the tubuloalveolar secretory units. ^, Bilateral nasolacrimal duct obstruction (NLDO) leading to dacryocystitis has been reported in oGVHD. ^, NLDO induced by epithelial and subepithelial inflammation and punctal occlusion—both inflammatory and spontaneous have also been observed. ^, Eyelids abnormalities (lagophthalmos, trichiasis, poliosis, entropion, and, less commonly, ectropion) occur due to chronic tarsal conjunctival inflammation, atrophic eyelid alterations, keratinization, and cicatricial changes. True cicatricial ectropion due to mechanical shortening of the anterior lamella caused by cutaneous involvement of GVHD has also been reported. Increased eyelid laxity in oGVHD, resulting from higher elastolytic enzyme (like MMP-9) activity mediated by the chronic inflammatory process both due to GVHD and systemic malignancy, compounds the ocular discomfort symptoms and ocular surface signs. Eyelid skin may exhibit scleroderma like skin lesions, pigmentary discolorations, vitiligo, and dermatitis. The other less commonly seen signs which may be seen in chronic oGVHD include cataract, episcleritis, scleritis, posterior scleritis, anterior uveitis, vitritis, serous choroidal detachment, and reduced corneal subbasal nerve plexus densities, herpetic keratitis, and cytomegalovirus retinitis.

Newer Diagnostic Modalities

Though a number of new diagnostic methods have been added to the armamentarium of DED diagnostics, there is no single adequate test for oGVHD diagnosis with a combination of clinical parameters and investigational modalities being recommended.

Meibography is the technique of in vivo observation of meibomian glands. Meibography in oGVHD shows complete or partial Meibomian gland loss/atrophy, structural alteration such as distortion or dilation of ducts. ^{, ,} Occasional finding of slender MG either pre- and early post-HSCT has been attributed to long-term immunosuppression causing sebaceous hyperplasia which results in obstruction MGD and can be reversed in some cases. As MG loss seen prior to the allo-HSCT can progress rapidly following oGVHD onset, noninvasive meibography for routine evaluation of hematological malignancies patients prior to and at regular follow-up posttransplant has been recommended. A cut-off value of 40% of MG area calculated using image analysis software has been adopted for diagnosing MGD in oGVHD patients. Consensus on correlation of MG area loss on meibography to oGVHD severity is not conclusive with some in agreement ^, and few others ^, not concurring. The same also applies to correlation between ocular surface clinical parameters and MG loss on meibography. ^{, ,} Hence, besides local inflammation there seems to exist a multifactorial etiology for MGD in oGVHD ( Fig. 7.3 ). Noncontact tear interferometry visualizes the interferometric pattern of the lipid layer of tear film and measures its thickness, thereby providing a functional MG assessment. A higher grade of severity of lipid layer interferometric pattern changes has been seen in oGVHD patients, with greater instability of the lipid layer in oGVHD patients as compared to Sjögren’s syndrome. While different tear interferometric patterns have been described to correlate with different subtypes of DED, inadequate tear volume makes it difficult to observe a typical interference pattern in severe aqueous-deficient (AD) Sjögren’s syndrome, oGVHD or Stevens–Johnson Syndrome. oGVHD with afflictions of lacrimal gland and MG manifests a combined AD-evaporative DED and shows a reduced lipid layer thickness in tear interferometry in comparison to non-oGVHD and healthy eyes.

Meibomian Gland Dropout—Lipiview in a healthy subject (A) and oGVHD patient (B) . Infrared meibography: Infrared meibography shows normal Meibomian gland architecture rather in oGVHD patients there is severe truncation and dropout of the Meibomian glands.

In Vivo Confocal Microscopy changes in oGVHD include decreased corneal epithelial cell density, epithelial dendritic cell, conjunctival epithelial immune cell, increased goblet immune cell, ^, anterior stromal cell density, anterior stromal extracellular matrix accumulation (reflective of engraftment of donor fibroblasts or altered fibroblast cell populations in the host cornea), reduced subbasal nerve number and density, altered branching, reflectivity and increased tortuosity, and altered conjunctival epithelial and stromal immune cell density. IVCM changes seem to correlate well with disease severity scores (Japanese Dry Eye score, ICCGVHD). IVCM can be a useful tool to study the cellular structural changes in DED with and without GVHD. ( Fig. 7.4 ).

In vivo confocal microscopy (HRT3) of the epithelium, nerve plexus, and stroma from a healthy and definite oGVHD patient. In the healthy subject the nerves appear as solid lines with no interspersed cells (A1, A2, and A3). The epithelium shows “honeycomb” appearance without any central reflectance. In definite oGVHD two abnormal patterns are seen on confocal microscopy (B1, B2, B3, C1, C2, and C3). In the first pattern, numerous inflammatory cells are present alongside corneal nerves. In the second pattern, there is absence of corneal nerves and the surface epithelium shows a central reflectance within the honeycomb area. In the second pattern, the stroma also shows increased reflectance.

Tear film osmolarity is a global indicator of DED irrespective of the subtype or etiology and is considered its best single predictor with a cut-off value of >310 mOsm/L for diagnosing oGVHD (98.4% sensitivity and 60.7% specificity). A cut-off value of 312 mOsm/L has been recommended for differentiating definite oGVHD (as per ICCGVHD criteria) from non-oGVHD (sensitivity of 91% and specificity of 82%). There is a significantly raised tear osmolarity in oGVHD with good correlation with severity of clinical parameters (Schirmer’s, TBUT, OSDI, and staining scores) and increasing disease severity. ^{, ,} Currently, tear osmolarity in isolation is not recommended to diagnose oGVHD but is a useful supplement to clinical dry eye tests used in oGVHD diagnosis in post-allo-HSCT. ^, A novel digital imaging analysis technique for quantification and morphological characterization of CFS which may help distinguish DED due to Sjögren’s and oGVHD has been recently proposed by Pelligrini et al. Shimizu et al. evaluated corneal higher-order aberrations (HOAs) using Zernike analysis in anterior segment optical coherence tomography (CASIA system, SS-1000, Tomey, Japan) and found higher corneal HOAs in chronic oGVHD eyes than the non-GVHD and normal eyes, which correlated with visual acuity and severity scores.

Role of Tear Biomarkers, Inflammatory Mediators, and Protein in Diagnostics

The immune reaction in GVHD comprises donor T-cells trigger of host antigen-presenting cells, which activate the donor effector T-cells to mediate the target tissue damage. The precise role of the various subtypes of T-cells, cytokines, and B-cells is not clear. Though CD4+ and CD8+ T-cells are the predominant infiltrates in ocular surface tissues in chronic oGVHD. Studies evaluating tear cytokines in oGVHD found raised ICAM-1 (intercellular adhesion molecule 1), IL (interleukin)-1Ra, IL-2, IL-1 β, IL-6, IL-8, IL-10, IL-2AP70, IL-17A, IFN (interferon)-γ, TNF (tumor necrosis factor)-α, MMP (matrix metalloproteinase)-9, and VEGF (vascular endothelial growth factor). ^, Recent reports of increased conjunctival neutrophil infiltration and tear inflammatory mediators produced by neutrophil elastase, MMP-9, MMP-8, and MPO (myeloperoxidase) highlights the role of neutrophils in oGVHD immunopathogenesis with these neutrophils releasing nuclear chromatin complexes as extracellular DNA (eDNA) webs that are termed neutrophil extracellular traps (NETs). oGVHD is associated with excessive accumulation of NETs which are recognized to be contributory to pathologic changes (corneal epitheliopathy, conjunctival fibrosis, ocular surface inflammation, and MGD) seen. Neutrophil secreted biomarkers [eDNA, neutrophil gelatinase-associated lipocalin (NGAL), Oncostatin M (OSM) and TNF superfamily member14 (TNFSF14)] could be useful in differentiating DED due to oGVHD from other etiologies.

Treatment

A multidisciplinary approach and coordination with the HSCT team is imperative in management of oGVHD. In recent times, with greater emphasis on organ-specific treatment, increasing systemic immunosuppression is no longer considered an optimal treatment approach for organ-specific GVHD.

Because oGVHD can progress rapidly to irreversible functional loss and scarring, it is imperative to start effective treatment early and then taper medication down. The preferred approach is a rapidly control of the disease and step-down approach. The three-pronged treatment approach, as adopted in other ocular surface immune-mediated inflammatory diseases, comprises lubrication, prevention, and control of tear evaporation, and most importantly, reducing ocular surface inflammation.

Conclusion

GVHD is the major cause of morbidity and mortality in patients after allogeneic hematopoietic cell transplantation. oGVHD is not just another dry eye disease. It is a rapidly progressive immunological disease that can lead to severe and irreversible ocular disease. It could involve the whole ocular surface, requiring a multipronged approach of treatment. There is no single treatment that can work but a combination of eye drops (serum tears and tear substitutes). There is a window of opportunity where a step-down treatment can reduce symptoms. The best approach is to have a baseline examination before BMT and in intervals after the BMT to detect any early ocular surface disease that may cause irreversible damage.