**4. The use of oct in Conjunctival pathologies**

#### **4.1 Conjunctival tumors**

One of the most studied and validated applications of ASOCT regards conjunctival tumors.

Many reports [18–24] demonstrate that the OCT study of conjunctival tumors can help the clinician to: make the diagnosis, help to distinguish among different types of neoplasm or between benign and malign neoplasms, help to assess the follow up after the surgical excision of the tumor.

The classification of the conjunctival tumors may be summarised in the congenital and acquired lesions.

The acquired lesions can be distinguished in: pigmented and non-pigmented or, depending on the origin of the mass, in surface-epithelial, melanocytic, fibrous-vascular, myogenic, neural, lipomatous, lymphoid, histiocytic, leukemic or metastatic.

Essentially the most studied conjunctival lesions are the pigmentedmelanocytic. This family of lesions includes nevus, racial melanosis, PAM (primary acquired melanosis) and melanoma. Among the non-melanocytic neoplastic lesions, the most frequently studied are squamous cell carcinoma and lymphoma.

#### *4.1.1 Nevus*

Nevus is the most common melanocytic tumor of the conjunctiva. It shows up as a discrete variably pigmented, slightly elevated sessile which usually remains quite stable during life with <1% risk of transformation into malignant melanoma. Histopathologically, a conjunctival nevus is composed of nests of benign melanocytes in the stroma near the basal layers of the epithelium.

A periodical follow-up, together with photographic comparison, is the best way to verify whether it is growing: sometimes you may need the mass excision if any growth is documented.

#### *4.1.1.1 OCT appearance*

The study of Shields et al. on 22 conjunctival nevi demonstrated that all margins of conjunctival nevi can be observed through ASOCT (high resolution in 100% of anterior borders and 82% of posterior borders). The sensitivity of AS-OCT for the detection of intrinsic cysts in a conjunctival nevus is 80%, its specificity is 100%, its positive predictive value is 100%, and its negative predictive value is 60% [22].

Regarding conjunctival nevi we can conclude that ASOCT seems to be more accurate in assessing the extent of these tumors as long as the nevus is not very thick and not heavily pigmented.

AS-OCT can also be used for differentiating a nevus from melanoma: unlike melanomas, the nevi usually contain intralesional cystic space (their presence usually confirms a chronic pathology) [21].

(Note that it is still debated whether the presence of cysts does not definitively rule out malignancy.)

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*OCT Applications in Conjunctival Disease DOI: http://dx.doi.org/10.5772/intechopen.87162*

*4.1.2.1 OCT appearance*

*4.1.3 Squamous cell neoplasia*

*4.1.3.2 OCT appearance*

neoplasia (CCIN) is possible.

*4.1.4 Squamous cell carcinoma*

enough to assess intracellular characteristics.

epithelium [23].

*4.1.2 Primary acquired melanosis (PAM)*

invasion of the subepithelial space [21].

underlying stroma. (squamous cell carcinoma).

white plaque (leukoplakia) may be present.

*4.1.3.1 Conjunctival intraepithelial neoplasia (CIN)*

full thickness replacement by abnormal epithelial cells.

Primary acquired melanosis, a frequent benign conjunctival pigmented lesion, can evolve into conjunctival melanoma. It is usually observed in middle-aged or elderly patients and, in contrast with conjunctival nevus, it is patchy, flat, and noncystic and it is usually not well circumscribed. This lesion may arise with or without atypia, and the presence of the atypia leads to a 50% chance of melanoma [25].

Histopathologically, PAM is characterized by the presence of abnormal melanocytes near the basal layer of the epithelium so the PAM ASOCT images is characterized by normal thickness but moderately hyperreflective basal epithelium with no

Squamous cell neoplasia may be classified in CIN or squamous cell carcinoma,

CIN (others prefer the terms mild, moderate, or severe dysplasia) appears as a fleshy, sessile or minimally elevated lesion usually arising at the limbus in the interpalpebral fissure and less commonly in the forniceal or palpebral conjunctiva A

Histopathologically, it is characterized by the presence of immature abnormal cells. The several types of displasia depend on the presence of these abnormal epithelial cells which may partially (mild dysplasia), nearly fully (moderate dysplasia) or fully replace (severe dysplasia) the normal cells. Carcinoma-in-situ represents

Due to its epithelial onset, distinctive criteria of ASOCT are a thickened, hyper-reflective epithelial layer with an abrupt transition from normal to abnormal

In the different types of CIN the authors found thickened hyperreflective epithelium and abrupt transition from normal to hyperreflective epithelium. Their results demonstrated that macroscopically resolved residual tumor nodules can be visualized by UHR-OCT [26]. A disadvantage of UHR-OCT is that it is not high

Shousha et al. [26] demonstrated that the use of UHR-OCT (ultra-high resolution OCT) in the diagnosis and follow-up of conjunctival and corneal intraepithelial

As above mentioned, the SCC develops when the abnormal cells have invaded the stroma. Histopathologically, invasive squamous cell carcinoma is characterized

depending on whether it presents as a localized lesion confined to the surface epithelium (conjunctival intraepithelial neoplasia or dysplasia) or as a more invasive pathology which has broken through the basement membrane and invaded the
