Conjunctival lymphangiectasia is a rare condition in which the normal lymphatic vessels are dilated and prominent within the bulbar conjunctiva.²⁰ It occurs in two forms: a diffuse enlargement of lymphatics that appears clinically as chemosis or focal dilated lymphatics that manifest as a cyst or a series of cysts (“string of pearls”).⁴⁷ On clinical biomicroscopic examination, lymphangiectasia appears as channels containing clear fluid separated by diaphanous septate walls. In 1880 Leber used the term “Lymphangiectasia haemorrhagica conjunctivae” to describe a condition where the conjunctival lymphatics were filled with blood as the result of abnormal connections between conjunctival lymphatic and the conjunctival vascular system.⁵⁵ We report a series of 11 cases of biopsy-proven conjunctival lymphangiectasia, discuss the distinctive histological characteristics of this condition, and review the literature on conjunctival lymphangiectasia and its differential diagnoses.

We reviewed the computerized flies at the regional Ocular Pathology Laboratory based at the Western Infirmary, Glasgow, Scotland, between January 1995 and December 2010. We identified and reviewed 11 cases with the diagnosis of conjunctival lymphangiectasia. We compared our findings with those reported in the literature.

The patient characteristics are summarized in Table 1.

A 59-year-old woman presented with a one-year history of ocular irritation associated with persistent bilateral conjunctival swelling. This immediately followed an upper respiratory tract infection with associated conjunctivitis and was presumed to be of viral etiology. She had been treated with topical lubricants and corticosteroids with little benefit. Visual acuity was 20/20 in each eye. Slit lamp biomicroscopy revealed diffuse chemosis affecting the inferotemporal conjunctiva (Fig. 1 and Fig. 2). Anterior segment ocular coherence tomography was used to further delineate the abnormality (Fig. 3). A clinical diagnosis of conjunctival lymphangiectasia was suspected. Magnetic resonance imaging (MRI) of the orbits and head and neck were normal. Thyroid function tests, blood count, and serum biochemistry were normal. Excisional biopsy of the chemotic conjunctiva with amniotic membrane and fibrin glue was performed on each eye separated by an 8-week interval. Histologically both specimens demonstrated lymphangiectasia within the submucosa and squamous metaplasia of the surface epithelium. She remained asymptomatic during 12 months of follow-up with no evidence of recurrence.

A 53-year-old man presented with a 6-month history of ocular irritation and swelling OD. Five years before he had undergone primary nasal pterygium excision of the right eye with no conjunctival graft . Best corrected visual acuities were 20/20 in both eyes. The left eye was normal. Examination of the right eye revealed a cystic area located temporally within the bulbar conjunctiva and extending three clock hours. The clinical suspicion was conjunctival lymphangiectasia. MRI of the orbits and head and neck were normal. Thyroid function tests and serum biochemistry were within normal limits. Following informed consent he underwent excisional biopsy of the involved conjunctiva with fibrin-glue–assisted amniotic membrane transplantation. Histologically the excised conjunctiva showed numerous dilated lymphatics within the submucosa and squamous metaplasia of the surface epithelium. Two months following surgery, localized cystic chemosis developed temporal to the excised area. He has remained asymptomatic during 8 months of follow-up.

A 49-year-old man had a 2-year history of intermittent nasal bulbar redness and irritation in the left eye. He had been treated with topical corticosteroids during these episodes. Visual acuity was 20/20 in both eyes. The right eye was normal. Slit lamp biomicroscopy of the left eye revealed an area of thickened conjunctiva with cystic elements in the temporal bulbar conjunctiva that encroached onto the cornea in a wing-like fashion. Based on the clinical appearance a diagnosis of primary cystic pterygium was reached. He underwent excision of the pterygium with fibrin-glue–assisted conjunctival autograft. No sutures were used to secure the autograft. Histologically the specimen showed typical elastotic degeneration, with areas of lymphangiectasia within the submucosa. The patient has remained asymptomatic during 6 months of follow-up with no evidence of pterygium recurrence or chemosis.

A 48-year-old man had a 6-year history of intermittent nasal bulbar redness and irritation in the left eye. He used topical lubrications for symptomatic relief. Visual acuity was 20/20 in both eyes. The right eye was normal. Slit lamp biomicroscopy of the left eye revealed an extensive area of thickened conjunctiva that encroached onto the nasal cornea; a clinical diagnosis of primary pterygium was reached. Excision of the pterygium with fibrin-glue–assisted conjunctival autograft was performed. No sutures were used to secure the autograft. Histologically the specimen showed typical elastotic degeneration, with areas of lymphangiectasia within the submucosa (Fig. 4). The patient has remained asymptomatic during 8 months of follow-up with no evidence of pterygium recurrence or chemosis within the bulbar conjunctiva.

A 47-year-old woman had a 2-year history of recurrent irritation and swelling on the outer aspect of her right eye. She wore monthly disposable silicone hydrogel contact lenses. Best corrected visual acuity was 20/20 in both eyes. Slit lamp biomicroscopy revealed localized cystic swelling involving the temporal bulbar conjunctiva of the right eye with an overlying keratin horn (Figs. 5A, 5B). She underwent excision biopsy of the lesion under topical anesthesia. On histological examination the excised conjunctiva showed marked lymphangiectasia within the submucosa and squamous metaplasia and keratinisation of the surface epithelium (Figs. 5C, 5D). The patient has remained asymptomatic during 8 months of follow-up with no evidence of recurrence.

A 65-year-old man gave a 6-month history of swelling on the outer aspect of his left eye. He was treated with topical lubricants with limited effect. Visual acuity was 20/20 in both eyes. Examination of the right eye was normal. The left eye showed a localized area of superotemporal cystic chemosis of the bulbar conjunctiva in a classic “string of pearls” appearance (Fig. 6). Excisional biopsy of the involved conjunctiva was performed. Histological examination of the specimen showed lymphangiectasia within the submucosa and squamous metaplasia of the surface epithelium. The patient has remained asymptomatic during one year of follow-up despite de novo localized cystic chemosis temporal to the excised area.

A 33-year-old woman presented with a 1-year history of persistent irritation and redness of the inner aspect of the right eye. She used topical lubrications for symptomatic relief. Visual acuity was 20/20 in both eyes. Slit lamp biomicroscopy revealed a primary nasal pterygium encroaching 2 mm onto the cornea. There was no associated chemosis. As she was symptomatic, she underwent pterygium excision with fibrin-glue–assisted conjunctival autograft. No sutures were used to secure the autograft. Histological examination of the specimen confirmed a pterygium with elastotic degeneration within the submucosa and squamous metaplasia of the surface epithelium (Fig. 7). There was accompanying lymphangiectasia. The patient has remained asymptomatic during 5 months of follow-up with no evidence of pterygium recurrence or chemosis.

The lymphatic channels of the conjunctiva contain valves that allow for directed drainage towards the inner and outer canthi. Obstruction can occur in inflammatory and neoplastic disease. This obstruction leads to lymphangiectasia or, if extreme, lymphatic cysts. Excised tissue will show dilated channels lined by a flattened endothelium. The ultrastructural characteristics of ectatic lymphatic vessels do not differ significantly from a normal lymphatic vessel. The vessel is, however, dilated, and the surrounding lamina propria is often edematous, presumably because these dilated vessels leak. The channels may contain proteinaceous fluid or clusters of lymphocytes (Fig. 8A). This may be accompanied by squamous metaplasia and keratinisation of the overlying surface epithelium (Fig. 8B) as part of a reactive process related to local trauma. If necessary, dilated lymphatic channels can be differentiated from capillaries by immunohistochemical staining for D2-40, a sensitive and specific marker of lymphatic endothelium (Fig. 8C).²⁹ The surrounding lamina propria may contain scattered inflammatory cells or show fibroblastic proliferation or scarring, supporting the secondary nature of this process.

The human lymphatic system, first described in 1627 by Gasper Aselli,³⁰ functions to remove excess interstitial fluid and macromolecules from the extracellular space and transports this fluid through lymph nodes before returning it to the venous circulation.¹⁹ Despite its integral role in preserving tissue fluid homeostasis, the study of lymphatics remains at a rudimentary level when compared to blood vessels.¹⁰¹

Conjunctival interstitial tissue fluid enters through the initial lymphatic (blind-ended tubes that are made up of endothelial cells) located immediately under the epithelium. The cells are tethered to surrounding stroma by anchoring filaments that prevent the tubes from collapsing.¹⁴ The precise mechanism that drives fluid into these initial lymphatics has not yet been fully elucidated.¹⁰² We do know, however, that lymphatic flow is created by the development of fluid pressure gradients between the initial lymphatic and downstream collector channels.^69 and 102 Unidirectional luminal valves are present throughout the lymphatic system and prevent backflow,²² but these valves may not be completely effective, as Shields et al reported a case of retrograde metastasis of a preauricular cutaneous melanoma to the ipsilateral conjunctival lymphatics.⁸³

It was once thought that the conjunctivae were the only components of the globe and orbit to have a lymphatic drainage system; however, lymphatic tissue has been consistently found in the lacrimal gland and optic nerve in humans and in the orbital apex and extraocular muscles in other primates.^30 and 82 The distinguishing electron microscopic features of initial lymphatics that permit differentiation from vascular capillaries are well characterized.^{14, 30 and 82} Both conjunctival and corneal lymphatics have been identified using in vivo confocal microscopy and show features morphologically distinct from adjacent blood vessels and discrepancies with respect to leukocyte flow velocities, yet some descriptions make no reference to bulbar conjunctival lymphatics at all.^21 and 67

The organization of the conjunctival lymphatics has been delineated using vital dyes and is divided into several groups.^{60, 89 and 93} A pericorneal lymphatic ring (lymphatic circle of Teichmann) forms a dense plexus of tiny lymphatic vessels along the limbus measuring about 1 mm in size. These then coalesce as they leave the limbus, forming a system of larger radially orientated vessels. At between 4 to 8 mm behind the limbus, large collector channels run circumferentially (pericorneal lymphatic ring), and these receive lymph from the radial lymph vessels. It is thought that there are connections between the deep conjunctival venous plexus and the collector channels, and on occasion retrograde flow results in the lymphatic channel filling with blood (lymphangiectasia hemorrhagica). The collector channels drain into one or two trunks, and these drain towards the lateral and medial commissures, where they join the lymphatic outflow of the eyelids. ³⁶ There are no conjunctival lymph nodes. ⁹³ The subsequent drainage of the eyelid lymphatics was thought to be by two main groups of vessels. A medial group of lymphatic vessels drains the medial upper and lower eyelids and terminates in the ipsilateral submandibular lymph nodes; a lateral group of lymphatics drains the lateral ends of both eyelids and terminates in the ipsilateral superficial parotid lymph nodes. With the development of newer mapping modalities—namely, ^99mTechnetium lymphoscintigraphy—there is an appreciation of variability in drainage patterns between individuals. ⁷² The majority of lymphatic basins are located in the parotid and anterior cervical nodes. ^11 and 24

Recent advances in the field of molecular biology have permitted the identification of lymphatics from other than purely histological criteria.^2 and 49 This has been driven by the appreciation of the important role that lymphatics play in tumor metastasis and inflammatory conditions such as transplant rejection.^{1, 39, 51 and 104}Vascular endothelial growth factor receptor 3 (VEGFR-3), through it two ligands, VEGF-C and VEGF-D, is considered the major regulator of lymphangiogenesis.^{3, 49 and 95} Other molecular markers specific for lymphatic vessels include lymphatic vessel endothelium hyaluronic acid receptor and the novel monoclonal antibody D2-40.^13 and 46

Genetic mapping of the autosomal dominant form of hereditary primary lymphedema (Milroy disease) has identified that the disease can be attributed to a point mutation that inactivates VEGFR-3 signaling.⁴⁰ A murine model for this disease has been developed which has been used extensively to investigate the phenotypic consequences of deranged lymphangiogenesis.⁴⁸ Primary lymphedema in humans, resulting in congenital conjunctival lymphangiectasia, has also been reported in Klippel-Trenaunay-Weber and Turner syndromes.^8 and 75

Nevertheless, the vast majority of conjunctival lymphangiectasia cases seen in clinical practice are not congenital. Rather, they represent a secondary lymphedema following disruption or obstruction of lymphatic pathways by other disease processes or as a consequence of surgery or radiotherapy. Patients may present because of cosmetic concerns or, more frequently, local irritation from tear-film disturbances provoked by epibulbar irregularity.

The history must specifically elicit whether the patient is aware of a head or neck mass or has been treated for such tumors previously. Harris et al reported a series of six such patients, and although no cases of tumor recurrence at the primary site, regional nodes, or orbital apex were identified. Persistent chemosis was thought to represent surgery- and radiation-induced obstruction of lymphatic/venous outflow channels.³⁶ Similarly, cosmetic blepharoplasties are a recognized precipitant of conjunctival lymphangiectasia.^{23, 47, 58 and 68} In situations where conjunctival swelling is associated with hemorrhage, it is important to establish whether this is recurrent and the time course over which the blood clears. Clearing is reported to occur in 2–4 days, but may take several weeks, revealing persistent, ectatic, sausage-like conjunctival lymph vessels.^{6, 54, 60 and 81}

The history should identify medical conditions resulting in systemic hypoproteinemia (nephrotic syndrome, malnutrition), local venous hypertension (thyroid eye disease, orbital apex syndrome, cavernous sinus thrombosis, carotid-cavernous fistula), and increased vascular permeability (vasomotor instability, allergy), as all these can drive fluid into the interstitial compartment resulting in chemosis. Travel to West and Central Africa is relevant, as Loa Loa infestation can appear as sausage-like dilations within the conjunctiva.⁵

Examination to identify any local masses or lymphadenopathy within the head and neck is mandatory, and computerized tomography or MRI may be required. The laterality and location of the conjunctival swelling is determined. Experience suggests that lymphangiectasia is most likely to be located within the temporal conjunctiva or dependent when it is more extensive.^47 and 60 Where blood is present within these vessels, some may exhibit a horizontal fluid level where they are only partially filled.⁶⁰ A local cause of lymphatic obstruction can often be identified adjacent to the lymphangiectasia, in our experience typically a primary pterygium. Rarely is there active local inflammation identified in lymphangiectasia, with most eyes appearing white at initial presentation, presumably because the inciting inflammatory event causing lymphatic scarring has resolved.⁴⁷ As seen in Patients 3 and 4, the finding of lymphangiectasia in relation to a pterygium supports the contention that inflammation and stromal changes disrupt the lymphatic drainage, resulting in localized dilatation. To exclude other causes of chemosis, baseline blood count, blood urea nitrogen, electrolytes, serum albumin, and thyroid function tests are routinely checked. Once diagnosed, lymphangiectasia can be a challenging condition to treat, as the nature of the preceding lymphatic obstruction can rarely be identified.

Several strategies to treat conjunctival lymphangiectasia have been described, typically reported as small case series. Direct excision of the affected conjunctiva can be successful.^{85, 92 and 93} Meisler et al described localized resection of all involved bulbar conjunctiva down to bare sclera.⁶⁵ All patients remained asymptomatic and recurrence-free at one year. An earlier series where the lymphangiectasia was simply biopsied to facilitate tissue diagnosis, the chemosis persisted, implying that the whole lesion must be excised.⁴⁷ Liquid nitrogen cryotherapy is effective; recurrences are common, but these are amenable to retreatment.^27 and 28 Isolated reports detail other modalities, specifically fractionated beta-irradiation and carbon dioxide laser ablation.^{7, 44 and 91} In cases of lymphangiectasia haemorrhagica, both surgical excision and diathermy of the abnormal communication between the conjunctival vessels and lymphatics have been described.^{6, 15 and 57} A refinement of the thermal coagulation principle has been reported. Lochhead and Benjamin used an Argon laser to obliterate the junction between the blood vessel and lymphatic.⁶⁰ Three patients were treated, the procedure was well tolerated, and no recurrences occurred during the follow-up period of one year.

Rarely, after procedures that involve extensive conjunctival manipulation such as blepharoplasty and scleral buckling, prolonged postoperative dependent bulbar chemosis occurs.^9 and 62 Although none of these reports include conjunctival histopathology, it is likely that the chemosis develops in response to damage to local lymphatics.⁵⁸ In many cases spontaneous resolution occurs, presumably due to lymphangiogenesis; however, the chemosis may be persistent.⁶⁸ Enzer and Shorr emphasize that, in such situations, stretching of the inferior forniceal ligaments occurs, and these must be surgically reattached to the orbital floor if initial simple measures such as pressure patching fail.^23 and 37 In our series we initially performed direct surgical excision; although more recently we have incorporated the use of cryopreserved amniotic membrane grafts. Wide experience has been reported with such grafts in the context of ocular surface reconstruction with excellent results.^64 and 76 It should be appreciated that isolated conjunctival lymphangiectasia may be identified not infrequently during clinical examination. Often it is not symptomatic, but in a minority of cases it can be a cause of persistent ocular irritation. In such situations, many patients respond to topical steroids, which suppress conjunctival inflammation; only in those individiuals where chronic lymphatic scarring and ectasia supervenes is surgical intervention indicated.

With rare conditions such as lymphangiectasia, where there are no randomized controlled trials, it can be difficult to determine which surgical intervention has the best chance of success. We feel that our technique using amniotic membrane, which empirically attempts to minimize further local tissue trauma, has much to recommend it.

Conjunctival inclusion cysts are common, accounting for 22.5% of all acquired epithelial lesions, and 80% of all cystic lesions, of the conjunctiva.³² The incidence is equal between men and women, with an average age of onset of 47 years.³² They are classified as primary or secondary, depending on their etiology. The primary or congenital inclusion cyst is usually located to the superomedial portion of the orbit and develops during the embryonal period as the result of separation of a portion of conjunctival epithelial cells.⁴¹ The secondary or acquired inclusion cyst is more prevalent than the primary cyst and is located most commonly in the superolateral aspect portion of the orbit. Acquired inclusion cysts form as the result of implantation of conjunctival epithelium underneath the stroma following injury or surgery, but may occur spontaneously by the amalgamation of mucosal folds that result from irregularly elevated surface epithelium in inflammatory conditions.⁸⁴

Acquired inclusion cyst formation has been reported following surgery where the conjunctiva is disturbed, including strabismus surgery, vitreoretinal surgery, cataract surgery ,and sub-Tenon’s anesthesia.^{10, 70, 90,97 and 99} Spontaneous inclusion cyst formation has been reported in association with pterygia and in longstanding chronic vernal keratoconjunctivitis.^52 and 56 The cysts may present many decades after the surgical procedure, particularly strabismus surgery.⁹⁰ They can be unilocular or multilocular. Histopathogical examination reveals that the cysts are lined by non-keratinizing stratified epithelium with occasional goblet cells. There may be scattered chronic inflammatory cells within the substantia propria, and if the cyst is longstanding, foci of dystrophic calcification may be present. The cysts are filled with clear fluid that often contains desquamated cellular debris.⁸⁷ Indications for removal include unacceptable cosmetic appearance, limitation in ocular motility, induced astigmatism, and ocular irritation.^{52, 90 and 97}Excision biopsy is the standard, although cauterization at the slit-lamp and Nd:YAG laser ablation has been used successfully for acquired cysts.^{18, 38 and 53}

The conjunctival nevus is the most common melanocytic tumor of the conjunctiva and has a benign natural history, with less than 1% developing into malignant melanoma.⁸⁷ A nevus typically becomes clinically apparent during the first or second decade of life as a discrete, variably pigmented, slightly elevated lesion that may contain fine, clear cysts.⁸⁸

Histologically, the structure of conjunctival nevi is similar to those found on skin, namely junctional, compound, and subepithelial. The nevus tend to be well circumscribed, non-encapsulated with nests of benign melanocytes in the stroma near the basal layers of the epithelium. A unique feature of conjunctival nevi, distinct from skin nevi, is the presence of large number of epithelial nest and cysts.⁷⁹ These cysts are found in 40–70% of all conjunctival naevi and are composed of a stratified squamous epithelial lining and occasional goblet cells.⁴² It is hypothesised that the epithelial tissue is dragged down as the initial junctional nevus descends into the substantia propria and becomes a compound nevus.²⁶ With time the intraepithelial component of the nevus may be lost completely, and thus only the subepithelial component persists, resulting in a subepithelial nevus. Cysts are noted in 70% of compound nevi, 58% of subepithelial nevi, and 40% of junctional nevi.⁸⁶ In children,conjunctival nevi excised because of documented rapid growth frequently show a marked local inflammatory infiltrate.¹⁰³

Although a historically accepted term, lymphangioma literally implies a neoplasm of lymphatic origin, these lesions are hamartomatous malformations, however, and their anomalous morphogenesis does not produce true lymphatic channels.³⁴

These lesions constitue a wide spectrum of malformations that are influenced when they occur during embryonic embryogenesis.^{43, 50 and 100} These can involve multiple orbital compartments, including both the palpebral and epibulbar conjunctiva.^{35, 45 and 78} Many are symptomatic because of mass effects, hemorrhage, and pain associated with acute enlargement.³³ These vascular malformations typically become apparent in the first decade of life, although rarely they may manifest much later, with the oldest presentation being in a patient aged 79.³⁵ There is a slight female preponderance.⁵⁹

Histological analysis reveals an ill-defined collection of lymphatic channels infiltrating normal tissues without a capsule.³⁵ The accumulation of vessels is more prominent than in lymphangiectasia. There is a variable amount of stroma showing evidence of smooth muscle, thereby belying a purely lymphatic lineage, hemosiderin-laden macrophages (if subject to repeated hemorrhages), and a variable lymphocytic component.⁵⁹ In some cases the lymphocytic elements are arranged into lymphoid aggregates forming subendothelial follicular structures.⁹⁶

Conjunctivochalasis describes the condition where there is redundant, loose, non-edematous inferior bulbar conjunctiva interposed between the globe and the lower eyelid margin.⁶⁶ It is invariably bilateral, although it may be asymmetric, being most prevalent in the elderly.⁶¹ Mechanical disruption of normal tear outflow occurs from interference by the redundant conjunctiva with the inferior tear meniscus and direct occlusion of the lower punctum.⁶¹ Patients complain of intermittent epiphora, ocular irritation or frank pain, and recurrent subconjunctival hemorrhage.⁷¹ Otaka and Kyu suggested that the redundant conjunctival folds were found at the lower-lid margin rather than the upper because of gravity.⁷⁴

Meller and Tseng propose that chronic ocular surface inflammation causes the accumulation of collagenolytic enzymes in tears resulting from delayed tear clearance and may be linked to the development of redundant bulbar conjunctiva.⁶⁶ A subsequent study by Watanabe et al did indeed find morphologic degenerative changes in the conjunctiva with fragmentation of elastic fibers and loss of collagen fibers in all cases, although there was no evidence of chronic inflammation.⁹⁸ Instead they hypothesised that purely mechanical forces between the lid and conjunctiva impaired lymphatic flow resulting in microscopic lymphangiectasia, which in turn led to the development of conjunctivochalasis. Others have not found any evidence of lymphangiectasia in such patients, but did find chronic tissue inflammation in association with functional nasolacrimal blockage.^12 and 16 Fraunfelder reported one case that presented with diffuse lymphangiectasia in the right eye and conjunctivochalasis in the left eye, demonstrating that these conditions can coexist.²⁷

Seasonal allergic conjunctivitis (SAC), or hay fever, is the most common form of ocular allergic disease and is associated with sensitization and exposure to environmental allergens, in particular grass and ragweed pollens.⁶³ Perennial allergic conjunctivitis (PAC), typically triggered by house dust mites and animal dander, is considered a less severe variant of SAC characterized by year-round symptoms, but with seasonal exacerbations experienced by 79%.¹⁷ Both conditions have an onset in childhood or early adulthood with no sex predilection. Affected individuals often have a history of atopy.³¹ Symptoms are invariably bilateral,^l but may be asymmetric and consist of red, itchy eyes, with associated burning discomfort and watery discharge. Both SAC and PAC are examples of a type 1 IgE-mediated hypersensitivity reaction. The primary inflammatory cells involved in ocular allergy are mast cells, which reside within the substantia propria.⁷³

Clinical examination reveals mild conjunctival hyperemia with a papillary reaction. In severe cases there is chemosis as a result of increased tissue fluid, most marked in the bulbar and lower tarsal conjunctiva. This gives the eyes a characteristic glassy appearance. Although rarely performed in clinical practice, histological analysis of conjunctival specimens from SAC and PAC patients demonstrates increased numbers of mast cells in the stroma, and infrequently within the epithelium itself.⁴ There may be stromal edema and increased numbers of conjunctival goblet cells.⁶³

Ataxia telangectasia (AT; Louis-Bar syndrome) is a rare autosomal recessive disorder characterized by early-onset progressive cerebellar ataxia, immunodeficiency, dysarthria, oculocutaneous telangiectasia, and abnormal ocular motility (nystagmus, pursuit and saccadic abnormalities, strabismus), and poor convergence and accommodation.²⁵ In the United States the incidence has been reported as 1in 30,000 live births.⁹⁴ The responsible gene, ATM (AT mutated), located on chromosome 11, was identified in 1995.⁸⁰ The telangectasia are always bilateral and are most prominent on the interpalpebral conjunctiva.²⁵These vessels increase in tortuosity and become progressively more dilated over the years.⁷⁷Telangiectasia of the skin may subsequently develop; the regions most commonly affected are the malar eminence of the face and pinnae of the ear. Unlike lymphangiectasia conjunctivae hemorrhagica where the blood-filled vessels appear then clear within a matter of days, in AT they are persistent and progressive. The vascular changes appear to have no significant effect on ocular comfort in most patients, although some are photophobic.²⁵ Histopathological analysis of bulbar conjunctival tissue from AT patients demonstrates increased numbers of blood vessels and greater variability in vessel caliber than control tissue from the ipsilateral inferior fornix.⁷⁷

Conjunctival lymphangiectasia has received scant attention in the medical literature, yet incidental sausage-like conjunctival cystic lesions are not infrequently seen during anterior segment examination. These require no intervention unless they result in persistent ocular surface irritation that is refractory to topical anti-inflammatories and lubrication. The vast majority are thought to represent secondary lymphangiectasia, developing as a consequence of a prior inciting stimulus, resulting in persistent local lymphatic scarring or distal mechanical outflow obstruction. Typically the patient does not recall this preceding event, nor is it clinically apparent. True primary conjunctival lymphangiectasia is rare and is only seen where there is a generalized failure of lymphatic development, as a result of deranged VEGFR-3 signaling.

A search of the PubMed database 1966–2010 was conducted using various combinations of the key wordsconjunctiva, lymphangiectasia, lymphangiectasis, lymphatics, chemosis, swelling, cyst, and hemorrhage. Articles in all languages were considered, provided that the non-English articles included English abstracts. Relevant articles that were cited in the reference lists of the retrieved articles were also included.

The authors reported no proprietary or commercial interest in any product mentioned or concept discussed in this article.