Ectatic corneal disease (ECD) comprises a group of disorders characterized by progressive thinning and subsequent bulging of the corneal structure. Different phenotypes have been recognized, including keratoglobus, pellucid marginal degeneration (PMD), and keratoconus (KC). Keratoconus has been widely investigated throughout the years, but the advent of laser refractive surgery boosted an immediate need for more knowledge and research about ectatic diseases. This article discusses nomenclature of ectatic disease, etiology and pathogenesis, along with treatment options, with special focus ok KC and forme fruste keratoconus.

Ectatic corneal diseases are a group of disorders resulting in progressive corneal steepening and thinning. Keratoconus, keratoglobus, pellucid marginal degeneration, post-keratorefractive ectasia, and corneal graft ectasia are the types of corneal ectasia. Early diagnosis with appropriate diagnostic tools can help prevent progression, eliminating the need for corneal transplantation. Lamellar or full thickness corneal transplantation are the treatment options for advanced diseases. Although the visual outcomes of penetrating keratoplasty are comparable to anterior lamellar keratoplasty (ALK) especially in keratoconus, ALK is the preferred treatment of choice considering benefits including reduced graft rejection, less long-term complications, and better graft survival. This article reviews the various surgical techniques in ALK with its clinical outcomes in advanced keratoconus.

We report a rare case of bilateral keratoglobus with hypermature intumescent cataract in a 55-year-old woman. Clinical examination and corneal topography confirmed generalized corneal bulging and global corneal thinning. A Pentacam® (Oculus Optikgerate, Wetzlar, Germany) demonstrated bilateral diffuse corneal thinning (368 μm in the right eye and 371 μm in the left eye). Phacoemulsification was performed in the right eye after thorough workup and modification of the surgical technique. This case report helps in better understanding of the challenges of cataract surgery and intraocular lens selection in a keratoglobus patient, and stresses the need for both thorough preoperative planning and intraoperative surgical modifications.

Pellucid marginal degeneration (PMD) is a non-inflammatory ectatic corneal disease characterized by a narrow band of corneal thinning separated from the limbus by a relatively uninvolved area 1-2 mm in width. It is a rare corneal disorder that shares many clinical characteristics with other corneal ectasias, such as keratoconus, keratoglobus or Terrien marginal degeneration. PMD usually starts later in life than keratoconus and progresses slower than keratoconus. Slit-lamp examination is very useful to distinguish PMD from other corneal ectatic disorders with inflammatory nature. Corneal topographic indices and the classical crab-claw topographic pattern cannot be used as the main tool to distinguish between PMD and keratoconus. New Scheimpflug imaging-based devices have shown the importance and usefulness of the pachymetric map for an appropriate diagnosis of PMD. In addition, biomechanical and densitometric properties have been studied as complementary techniques to help in the diagnosis of PMD.

We report the case of a 3-year-old boy presenting with bilateral keratoglobus and blue sclera in addition to hallux valgus, arachnodactyly, small joint hypermobility, mitral valve dysfunction and a history of generalized muscular hypotonia in early infancy. Molecular genetics provided evidence of two pathogenic mutations in the ZNF469 gene (compound heterozygosity) leading to the diagnosis of brittle cornea syndrome type 1. In addition to neuropediatric care, spectacles were prescribed to correct refractive error and for ocular protection. Owing to the thin cornea and sclera, eye injuries are the main cause for irreversible visual loss in this disease.

Anterior megalophthalmos and keratoglobus are characterised by corneal thinning and deep anterior chamber. They are clinically distinguished on the basis of normal to slightly decreased corneal thickness with a large corneal diameter (>13 mm) in case of anterior megalophthalmos, and marked limbus-to-limbus corneal thinning with globular protrusion in keratoglobus. To achieve and maintain a centred and stable intraocular lens (IOL) position in the bag is often difficult in cases of anterior megalophthalmos due to a too large diameter of the capsular bag and ciliary ring. We report a case of a 40-year-old man with features of anterior megalophthalmos with extremely thin cornea. He had spontaneous posterior dislocation of IOL and capsular tension ring (CTR) within the bag after initial successful cataract surgery. The dislocated complex could neither have been repositioned with scleral fixation due to large diameter of ciliary ring nor could it have been explanted through a clear corneal incision due to associated very thin cornea. We performed pars plana vitrectomy and separated the IOL-CTR complex inside the eye and explanted them separately through the sclerotomy, as is done for removal of intraocular foreign body. This avoided incision on the thin cornea. We conclude that this method can be very useful in a similar clinical situation but is complex enough to justify its use in routine cases.

We aimed to describe congenital keratoglobus with blue sclera in two siblings with overlapping Marshall/Stickler phenotype. Two sisters (ages four and six) with bilateral high astigmatism were evaluated by slit-lamp microscopy. Corneal topography and pachymetry maps were also obtained. Slit-lamp examination revealed that both corneas were globular in shape with peripheral corneal thinning. Pachymetry maps showed diffuse corneal thinning. Two siblings had in common the features of keratoglobus, blue sclera, atypical face, hearing loss, and hypermobile joints. We tentatively diagnosed the sisters as having an overlapping Marshall-Stickler phenotype based on clinical and radiological findings. Marshall-Stickler syndrome may exist in the differential diagnosis of keratoglobus with blue sclera.

Brittle cornea syndrome is a rare generalised connective tissue disorder with ocular features like keratoglobus or keratoconus, severe corneal thinning and a high risk of perforation. Various authors in different case reports and case series have brought out the fact that brittle cornea is a disorder with characteristic systemic manifestations such as deafness, joint hypermobility, hyperelasticity of skin, kyphoscoliosis and dental abnormalities alongwith ophthalmic features. We report a case of globe perforation following trivial trauma, in an individual with brittle cornea without any extraocular manifestations, posing a challenge in the diagnosis and dilemma in surgical repair of cornea, restoration of globe integrity and visual rehabilitation. The absence of systemic manifestations decreased the index of suspicion and led to a surprise in the theatre-a point this case emphasised.

A juvenile to young adult, male, great horned owl (Bubo virginianus,GHOW) was presented to the wildlife rehabilitation hospital at Lindsay Wildlife Museum (WRHLWM) due to trauma to the right patagium from barbed wire entanglement. On presentation, both corneas were irregular, dry, and no movement of the third eyelid was noted. A severe corneal enlargement/globoid appearance was the predominant ophthalmic feature. The fundus was normal in both eyes (OU). Over the course of several days, both corneas developed edema combined with further dessication at the ocular surface associated with diffuse dorsal fluorescein stain uptake. Repeated ophthalmic examinations found normal intraocular pressures and an inability to move the third eyelid over the enlarged corneas. The bird was deemed nonreleasable due to severe wing damage and poor prognosis associated with eye abnormalities and was humanely euthanized. Postmortem CT, enucleation, and histopathology were performed to evaluate the ocular anatomical abnormality and confirm the suspected diagnosis of keratoglobus. This GHOW represents the first reported case of presumptive keratoglobus in a raptor.

We present the case of successful repair of an exposed glaucoma drainage tube by cornea graft fixation with tissue adhesive, and without subsequent coverage by adjacent conjunctiva or donor tissues. Patient with history of keratoglobus with thin cornea and sclera, and phthisical contralateral eye, underwent three unsuccessful corneal grafts followed by Boston type 1 keratoprosthesis in the right eye. Ahmed drainage device with sclera patch graft was implanted to control the intraocular pressure. Two years later the tube eroded through sclera graft and conjunctiva. Repair was performed by covering the tube with a corneal patch graft secured by tissue adhesive after the conjunctiva in this area was dissected away. The cornea graft was left uncovered due to fragility of adjacent conjunctiva. The healing of ocular and graft surfaces was complete prior to the 1 month follow-up. Conjunctival epithelium covered the corneal patch graft. At 12 months follow-up, the graft and the tube remained stable. Our report suggests that corneal patch graft fixation to the sclera by means of tissue adhesive, without closing the conjunctiva, can be considered as an effective alternative surgical approach for managing exposed glaucoma drainage tube, accompanied by adjacent conjunctiva tissue deficiency. How to cite this article: Berezina TL, Fechtner RD, Cohen A, Kim EE, Chu DS. New Technique of Exposed Glaucoma Drainage Tube Repair: Report of a Case. J Curr Glaucoma Pract 2015;9(2):62-64.

Corneal ectasias include a group of disorders characterised by progressive thinning, bulging and distortion of the cornea. Keratoconus is the most common disease in this group. Other manifestations include pellucid marginal degeneration, Terrien's marginal degeneration, keratoglobus and ectasias following surgery. Advanced ectasias usually present with loss of vision due to high irregular astigmatism. Management of these disorders is difficult due to the peripheral location of ectasia and associated severe corneal thinning. Newer contact lenses such as scleral lenses are helpful in a selected group of patients. A majority of these cases requires surgical intervention. This review provides an update on the current treatment modalities available for management of advanced corneal ectasias.

Our objective is to evaluate the literature regarding selected genetic diseases of the cornea, including megalocornea, keratoglobus, keratoconus, cystinosis, the mucopolysaccharidoses, sclerocornea, Peters' anomaly, familial dysautonomia, and various corneal dystrophies. The transparency of the cornea is a consequence of uniformity in both size and spacing of the collagen lamellae. The cornea's clarity depends on a delicate biochemical and structural balance; consequently, genetic disorders that disrupt either its metabolic or anatomic function can cause opacity and vision loss. Many childhood corneal diseases have a genetic etiology and are associated with known syndromes. Each disorder has unique associated set of possible complications. Prognosis often depends on the extent of opacity and disorganization of the anterior segment. Corneal transplantation has been performed for these disorders with variable success.

Keratoglobus is a rare condition of bilateral corneal ectasia, which results in high myopia, irregular astigmatism, scarring, and rarely spontaneous globe rupture. Globoid protrusion of a clear, diffusely thin cornea is the pathology. The congenital form has been associated with blue sclera in which there is a systemic connective tissue disorder with abnormal collagen synthesis like Ehlers-Danlos syndrome, Marfan syndrome, and osteogenesis imperfecta. Some concomitant abnormalities reported with kertoglobus include joint hypermobility, dental and skeletal abnormalities, osteal fragility, and deafness. Acquired forms have been reported to be associated with vernal keratoconjunctivitis and thyroid ophthalmopathy. We report the case of a 16-year-old boy with keratoglobus who presented with a history of photophobia and a low vision in both eyes since birth. He has been followed up by our pediatric cardiology department due to multiple cardiac anomalies. He had hypermobility of large joints, easy bruising, thin and hyperextensible skin with visible veins, which were also described in his elder brother. We aimed to discuss the etiology and the association of keratoglobus with some systemic abnormalities caused by collogen tissue disturbance, and make a brief review about the recent literature concerning the management of keratoglobus patients.