Of late, renewed interest has been generated in Lamellar Keratoplasty (LK) and many forms of LK have been introduced. Deep Anterior Lamellar Keratoplasty (DALK), Superficial Anterior Lamellar Keratoplasty (SALK) or Tucked-In Lamellar Keratoplasty (TILK) is indicated in stromal pathology with healthy endothelium. These procedures have least risk of rejection. On the other hand, Descemet Stripping Automated Endothelial Keratoplasty (DSAEK), Descemet's Membrane Endothelial Keratoplasty (DMEK), and Pre-Descemet's Endothelial Keratoplasty (PDEK) are performed in diseased endothelium with healthy stroma. Authors have described three innovative techniques to better visualize and support the graft. These include—(1) Endoilluminator-assisted PDEK, (2) Air pump-assisted PDEK and (3) Host Descemetic scaffolding to support the graft.

Keratopigmentation or tattooing was a popular technique to mask corneal opacities in the past. However, the practice of tattooing has been greatly reduced after the introduction of keratoplasty. Alio and coworkers have devised special instruments and use micronized mineral pigments and claim “Keratopigmentation is a modern surgery that provides an excellent solution for patients where other treatment options are not suitable.”

Blood supply to optic nerve plays a vital role in the pathogenesis of glaucoma. The difference between arterial blood pressure and intraocular pressure (IOP) is defined as ocular perfusion pressure (OPP). There are published reports that patients with glaucoma have low OPP as compared to normal individuals. The quantification of blood flow in the eye can provide evidence about the pathological changes in optic nerve head. The cause of reduction of OPP is not known but seems to be vascular dysregulation or insufficient autoregulation. Authors have described both invasive and noninvasive methods of assessment of the ocular blood flow as well as local and systemic factors which influence it. They feel that data are not sufficient to validate use of ocular blood flow assessment for the treatment and prognosis of glaucoma.

Selective Laser trabeculoplasty is considered a relatively safe procedure in the management of glaucoma. Authors have briefly described the mechanism of action, indications and contraindications, advantages and disadvantages, complications and outcome of the technique.

Management of intractable glaucoma poses a great challenge to ophthalmologists. Glaucoma drainage device (GDD) forms a new bypass pathway for the aqueous humor. It is a useful device for the management of intractable glaucoma as it drains the aqueous from the anterior chamber into the subconjunctival space. GDDs are of three types—setons, valved implant and nonvalved implant. Authors have described step-by-step surgical procedure of implantation of the implant and its early and late complications.

There are a number of factors which influence the outcome of IOL implantation. One of the most important factors is the correct calculation of power of IOL. Ultrasound has been used for measurement of ocular parameters for the calculation of IOL power for quite a long time. However, these calculations do not reach within 0.50 diopters of the target refraction in 25% of cases, and some of the eyes present significant refractive surprise. Recently, biometers using optical partial coherence interferometry or optical low coherence reflectometry have been introduced. These biometers are user-friendly and accurate. Mohan and Chakrabarti presented a detailed account of advances in the calculation of IOL power determination.

Cataract operation is the most common surgery performed worldwide. Several measures have been adopted to make it safe and improve its outcome even in complicated cases. Chapters like Custom Cataract Surgery, Astigmatism Management in Cataract Surgery, Posterior Capsular Rupture Recognition and Management, Femtosecond Laser-assisted Cataract Surgery in Posterior Polar Cataracts, Pseudoexfoliation Cataract: Management and Phacoemulsification in Subluxated Lenses are included in this volume for the benefit of young ophthalmic surgeons so that they may become more careful and meticulous in performing the surgery in difficult patients. It is not rare to witness loss of capsular support in cataract surgery. The surgeon cannot implant IOL in the bag. The scleral fixed IOL is the right answer in such a situation.

It has become a fashion to cite clinical trials extensively without clearly understanding their application in real-life situations. Lingam Gopal deserves compliments for discussing how to adopt the results of trials in the management of retinal vascular diseases.

Optical Coherence Tomography Angiography (OCTA) is a noninvasive, high resolution imaging technique that provides angiographic maps of retina and choroid to study the blood circulation. It can diagnose ischemia of choriocapillaris and choroidal neovascular membrane (CNVM). Since OCTA presents a 3D view of tissues, it can detect minor abnormalities of the retina and choroid. In a comprehensive chapter, Chaitra and colleagues have described principle and procedure of OCTA and discussed the findings in normal retina and common retinal diseases such as diabetic retinopathy, retinal vascular occlusions, CNVM and age-related macular degeneration. OCTA can also be used to evaluate inflammatory diseases of retina and choroid, and intraocular tumors.

The chapter on the role of spectral domain-optical coherence tomography (SD-OCT) in the evaluation of diabetic retinopathy highlights the importance of examination of vitreomacular interface and inner and outer layers of retina. A relationship between disruption of ellipsoid zone and visual acuity has been found.

In this volume, the readers can also derive benefit from interesting chapters on Necrotizing Retinopathies, Nyctalopia, Ocular Burns and Cerebral Angiography.

We know that in the past few decades tremendous progress has been made in all fields of ophthalmology. This volume presents information on some of the advances. Hopefully, the postgraduate students, residents and general ophthalmologists will utilize the knowledge effectively for the better care of their patients.

Credit goes to Shri Jitendar P Vij (Group Chairman), Mr Ankit Vij (Managing Director) and Ms Chetna Malhotra Vohra (Associate Director–Content Strategy) for their interest in Recent Advances in Ophthalmology series. We appreciate the hard work of Ms Nikita Chauhan (Senior Development Editor) for elimination of plagiarism and staff of M/s Jaypee Brothers Medical Publishers (P) Ltd, New Delhi for nice production of the book.