Corneal blindness is the second most common preventable blindness in the world after cataract. In developing countries like India, out of 1% total corneal blind cases, half can be corrected by corneal transplant. Vitamin A deficiency, infections, trauma, improper use of contact lenses and inappropriate use of home remedies are the common causes of preventable blindness (Acharya et al. 2012). Worldwide approximately 45 million people are suffering from bilateral blindness and 135 million have severe bilateral vision impairment (Whitcher et al. 2001). As stated above, corneal transplant is a potential mean to correct treatable blindness. For the successful achievement of the transplant, a good cornea is of paramount importance. Previously corneas were stored in the moist chamber maintained at 4 °C. This technique was having a drawback of the endothelial insult due to the presence of the metabolic waste and other materials in aqueous humor. Corneal preservation witnessed a major breakthrough in 1965 when Capella, Kaufman and Robbins developed the technique of corneal tissue cryopreservation. This technique could able to maintain corneas for more than 1 year in transplantable state. Still the technique was suffering from few shortcomings like requirement of special equipment, trained technician and donor tissue removal in less than 6 h postmortem. In 1968, stocker developed a method to store the corneas in the homologous serum. This technique led him to transplant corneas stored for more than 4 days. This technique had a specific requirement of the serum of acceptor of the cornea (McCarey and Kaufman 1974). In 1968, Mizukawa and Manabe developed a preservation solution in which whole excised eyeball could be submerged. The medium was formulated using chondroitin sulfate, inosine, adenine, adenosine, penicillin and streptomycin. Almost 600 successful keratoplasties were done using this technique (Mizukawa and Manabe 1968). This revolutionary work became the basis for the development of future chondroitin sulfate-containing media. In March 1974, two scientists, Bernard E. McCarey and Herbert E. Kaufman, developed a storage medium which affected the storage of corneas in a greater way. The most important factor involved with this media was the non-requirement of the specialized techniques stated earlier. This modified tissue culture medium was given the name MK medium by them. MK medium is a mixture of medium 199 (containing cell nutrients, commercially made by Sigma Aldrich, US) and dextran with antibiotics. It is a buffered medium which has an osmolarity between 290 and 320 and a pH 7.4. After the development of medium, it was tested on the rabbit corneas where it is found to maintain them for 14 days (McCarey and Kaufman 1974). In 1984, intermediate storage medium was introduced by Kaufman and associates. Medium named K-sol contains 2.5 % chondroitin sulfate, modified medium 199 with HEPES. The medium contains gentamicin for the maintenance of the sterility. It was proposed to store and maintain them for 14 days, but acceptable storage days are from 4 to 7 days (Lindstrom 1990). After K-sol intermediate storage media Dexsol was introduced in 1988 by Chiron Ophthalmics Inc. In addition to 1% dextran, Dexsol contains 1.35 % of chondroitin sulfate (Kaufman et al. 1991). In order to study the corneal deturgescence ability of chondroitin sulfate, a study was done by Lindstrom and associates. They found that 1.5 % chondroitin sulfate was needed to maintain the normal human corneal thickness at 4 °C and 34 °C (Lindstrom 1990). In order to preserve corneas for longer time, Optisol was introduced by Chiron Ophthalmics Inc. which has 2.5 % of chondroitin sulfate along with 1 % dextran. A comparative study done between Dexsol and Optisol with human corneas found that corneas stored in Optisol were significantly less thick than with Dexsol (Kaufman et al. 1991). In the European countries, eye banks usually use organ culture medium. Organ culture method provides several advantages like long storage time, acceptance of corneas of longer postmortem time and detection of microbial contamination prior to transplant (Pels 1997; Frueh and Bohnke 2000). Components of organ culture are Eagle’s minimum essential medium (MEM) supplemented with 2 % fetal bovine serum (FBS). Few eye banks in Europe were found to use up to 8 % FBS (Armitage 2011). Several studies have shown superiority of the organ culture over hypothermic media (Armitage et al. 2014; Bohnke 1991). These days, adjoining of the two storage techniques, i.e., hypothermic and organ culture, is a current research area in the field of corneal storage (Haug et al. 2013) (Fig. 17.1).

To summarize, corneal storage media have done a long journey starting from short-term compromised storage to long-term improved storage. Still a lot is expected to happen to increase the lifespan of corneas to decrease the burden of preventable vision loss worldwide.

Tattooing solutions are used to mask the disfigured cornea. Tattooing solutions are used by ophthalmologist for cosmetically repairing the corneal opacities. There are different solutions used to tattoo the cornea. Tattooing with copper sulfate was introduced by Galen. In 1870 DeWecker used Indian ink for staining the cornea by mechanical means. In 1925 Professor Knapp introduced a method for coloring the discolored cornea by using gold chloride solution into the corneal stroma. The corneal tattooing should be done in such a way that it gives a good cosmetic effect along with permanent staining of the entire corneal opacity (Ziegler 1922; Pitz et al. 2002).

Gold or platinum chloride solutions are used for tattooing the discolored cornea. It is a simple, safe and effective method for coloring the cornea brown or black as compared to previously used Indian ink. For tattooing 2 % gold chloride or 2 % platinum chloride solution is used. The affected cornea is anesthetized by topical anesthesia and the corneal epithelium is removed from the area to be stained. Then with the help of a cotton-tipped applicator, 2 % gold chloride solution is applied to the affected area followed by 2 % hydrazine hydrate solution, till the affected area turns brown or black as desired. The tattooing technique with platinum chloride is similar to gold chloride tattooing (Duggan and Nanavati 1936; Pradhan et al. 2015) (Fig. 17.2).

Tattooing of the corneal opacities is a useful technique for the patients who are intolerant to cosmetic contact lenses. Tattooing of the cornea has got several advantages over wearing contact lenses. The patient is free from the maintenance of wearing a contact lens. In patient with peripheral corneal opacities with vision, corneal tattooing is an alternative to correct the cosmetic complaint without hampering the vision, whereas a colored contact lens may do so. It also gives social acceptance to the people (Pitz et al. 2002; Mannis et al. 1999).

Chemical ocular burns constitute true ophthalmic urgencies affecting extensively the cornea, surface epithelium, conjunctiva, anterior segment and limbal stem cell system leading devastating consequences, viz., chronic pain, disfigurement and vision impairment (Spector and Fernandez 2008). It is necessary to be diagnosed and treated at the earliest to prevent from potentially blinding ocular injuries and morbidity. It needs intensive evaluation of the burn, and prompt interventions should be given immediately to restore the integrity of ocular surface and tissues. Typically its occurrence is due to accidental ingress of corrosive substances into the surface of the eye or periocular tissues. Understanding the pathogenesis of these traumatic situation leads to the development of novel agents for the treatment. The major goal of the therapy is to rejuvenate the ocular surface and corneal clarity at optimal level needed for good sight.

The vitreous body is a natural polymeric hydrogel composed primarily of type 2 collagen and hyaluronic acid and performs the essential physiological functions of intraocular pressure maintenance and ocular nourishment. Disruptions in this delicate architecture lead to the separation of its components (syneresis), creating the conditions for vitreoretinal disease (Foster 2008). Vitreous substitutes have been in use for almost a century to repair numerous complex vitreoretinal conditions successfully, such as most retinal detachments, giant retinal tears, macular holes and complex detachments. The ideal vitreous substitute should mimic the native vitreous in both form and function and be transparent, nontoxic, elastic and biocompatible for the long term. For practical reasons, it should also be easily manipulable during surgery, easily available, stable during storage, injectable through a small syringe and available at a reasonable cost. Advances in vitreoretinal surgical techniques, instrumentation and material technology have led to an array of agents from which vitreoretinal surgeons can choose (Torsten and Caroline 2007). The vitreous substitutes can be classified based on their availability, composition and physical properties into the following types: