Like its predecessors, the 13th volume of RAO contains selected topics on cornea, uvea, glaucoma, retina and systemic diseases. Editorials on imaging in glaucoma and intravascular interventions in ophthalmic disorders are included to highlight the diagnostic treatment aspect of these diseases respectively.

Refractive lenticule extraction (ReLEx), small incision lenticule extraction (SMILE) is a bladeless and flapless procedure wherein a corneal lenticule is removed by femtoseconed laser. It is less invasive and does not cause dryness and is free of corneal flap complications. However, it is in an evaluation stage. SMILE has several limitations such as, it cannot treat hyperopia and takes longer time for visual recovery. On the other hand, laser-assisted in situ keratomileusis (LASIK) is an established technology which can provide good visual acuity in a short time. It has a versatile ablation profile and can correct all types of ametropia. Alio and coworker have presented a critical account of both types of refractive surgery.

Many patients with ocular tuberculosis may not present any evidence of primary tuberculosis. It is reported that only 1.4% of patients with primary tuberculosis develop ocular manifestations. Ocular tuberculosis is unilateral and asymmetrical. It may result from hematogenous spread. It may cause a wide spectrum of lesions ranging from ocular surface to optic nerve. Biswas and associates have described the ocular lesions of tuberculosis and summarized the ongoing research and development in the diagnosis and treatment.

Some cases of uveitis pose a challenge to the treating ophthalmologists because they are chronic, recalcitrant and sight threatening. They remain refractory to systemic corticosteroid and immunosuppressant therapy. Both these drugs cause unacceptable side effects; therefore, intravitreal administration of biologicals is considered relatively safer and effective. Majumder and Biswas described the importance of intravitreal therapy.

We know that diabetic macular edema (DME) is the leading cause of blindness in patients with diabetic retinopathy. A poor glycemic control, impaired blood retinal barrier integrity, release of vasoreactive substances and altered vitreoretinal interface play their complex role in the pathogenesis of DME. The control of metabolic factors, laser photocoagulation therapy, and vitrectomy are effective, sight-saving interventions. Das and associates have discussed DME in some details with the help of nice illustrations.

Classical case studies of postoperative endophthalmitis are presented by Verma and Chakravarti in the chapter on endophthalmitis. The pictorial case studies reveal not onlyFM14 the mode of presentations but also their response to the given treatment. Management of endophthalmitis mainly comprises intravitreal antibiotics and pars plana vitrectomy. Authors have described prophylaxis, availability of newer intravitreal antibiotics, cluster infection and legal issues related to endophthalmitis also.

Toxic anterior segment syndrome (TASS) may be confused with blinding endophthalmitis. Hence, it is also included in the volume. The differentiating points between these two conditions are detailed.

Prevention of postoperative endophthalmitis is a joint responsibility of operating surgeons, staff of the theater and paramedical staff. Viewpoints of an experienced microbiologist are projected in the chapter on control of infection in ocular surgery.

Oxidative stress, chronic inflammation and genetic and environmental factors largely contribute to the occurrence of age-related macular degeneration (AMD). Chandra and Kulkarni have reviewed the role of anti-oxidative stress therapies, anti-inflammatory therapies, visual cycle modifying agents, choroidal blood flow enhancing agents and regenerative stem cell therapies in the prophylaxis of AMD and concluded that these therapies lack definitive evidence of benefit. Therefore, Age-related Eye Disease Study (AREDS) formulation remains the mainstay of prophylaxis. Anti-VEGF agents have a definite place in the treatment of wet AMD, but they need repeated intravitreal injections, and develop drug resistance and tissue atrophy from chronic use.

Idiopathic polypoidal choroidal vasculopathy (IPCV) is an ill-understood clinical entity that has some common features of AMD. Whether AMD and PCV represent two different and distinct entities or are variants of the same disease? Gopal and coauthors have tried to answer these queries. Presence of orange nodules, large hemorrhages, absence of drusen and typical indocyanine green (ICG) angiography picture helps to differentiate the two different disease entities.

Chapters on ocular sarcoidosis, retinoblastoma, ocular surface disorder, macular phototoxicity, herpes, nystagmus, Behcet's disease, and cystinosis have also been included in this volume.

Recent developments in ophthalmology have significantly revolutionized the treatment of eye diseases and improved the quality of patient's life. It is hoped that readers especially postgraduates, and residents and general practitioners will find the book useful in the examination and day-to-day care of their patients, respectively.

We are thankful to Shri Jitendar P Vij (Group Chairman), Mr Ankit Vij (Group President) of M/s Jaypee Brothers Medical Publishers (P) Ltd, New Delhi, India, and staff for their continued interest in the publication of the Recent Advances in Ophthalmology Series.

This poor diagnostic performance is primarily a function of the huge inter-individual variability seen in optic disc morphology. Since, optic disc size itself shows an almost 600% variation. It is unlikely that any device would accurately classify optic discs as normal or glaucomatous with very high accuracies.³ This led to the realization that the true potential of imaging would be in the field of progression and reports demonstrated that imaging had the potential to detect change before it occurred on visual fields.

The advent of the GDx gave us the ability to actually measure the nerve fiber layer parameters and was a new clinical parameter entirely. It demonstrated extremely good diagnostic capability in the initial reports, subsequent reports however put its diagnostic ability on par with the other imaging devices. The GDx also had the misfortune of having three significant hardware changes during its lifetime. These were carried out as a way to minimize the effect that other birefringent structures had on the nerve fiber layer measurements. While this resulted in improved testing accuracy this came at the cost of no backward compatibility with earlier versions of the device. This effectively limited its utility in assessing progression since few patients had long-term follow-up on a single device. The advent of the spectral domain optical coherence tomography (OCT) effectively sounded the death knell for the GDx since you now had a device which could measure nerve fiber layer (NFL) at higher resolutions in addition to having retinal applications too.

While, the OCT revolutionized macular imaging, its impact on glaucoma was less dramatic with time domain technology. While, it was as effective as the HRT and GDx in detecting the disease there were concerns about the follow-up scans not being obtained from the same locations as the baseline scans because of poor image registration. This limited its utility in assessing progression as compared to the HRT where good image registration was available.

The resolution of the OCT was further enhanced with the spectral domain OCT. This was made possible by the improved hardware and the improvedFM22 computation power available. However, these generational changes were also backward incompatible rendering a lot of follow-up data useless. The HRT was in this respect an excellent tool because the hardware changes still permitted backward compatibility with earlier scans. The longest optic disc follow-ups for glaucomatous eyes is possibly available on the HRT because of the backward compatibility making it possible to use patient data from earlier devices for comparison. However, the HRT III will no longer be manufactured while support will be provided for existing devices. This has effectively limited the future utility of the HRT since most newly detected glaucoma patients would be imaged on the OCT.

The spectral domain OCT promised superlative resolutions. However, these resolutions are rarely seen in clinical practice partly because of issues with eye movements and scan artefacts. In spite of this, the level of detail available and measurement accuracies mean that it is better at detecting progression than earlier devices. However, the large number of device manufacturers is an issue since measurements between various devices are not the same and patients would have to be imaged on the same device for meaningful data on progression.

While the devices are helpful in classifying disease one must always remember that “abnormal” values on imaging are statistical abnormal and in the absence of corroborating clinical data should not be taken at face value as evidence of disease. The over diagnosis of glaucoma because of the so called “red disease” is very common and results in unnecessary medications and hardship to the patient. It is also worth keeping in mind that most normative databases include only eyes with “normal” optic disc morphology. There are very few macrodiscs or microdiscs. Tilted and otherwise anomalous discs are also not included. Using any imaging tool on such eyes will invariably result in abnormal results which do not necessarily indicate glaucomatous damage. It is also important to keep in mind that the imaging techniques perform better at detecting glaucoma progression early in the disease. In more advanced disease, perimetry is still more sensitive in detecting progression.

The adaptive optics devices promise almost cellular resolutions. They are currently limited by very small image windows which limit their utility in glaucoma detection.

Further improved resolutions and testing algorithms on the OCT will make it possible to perhaps detect progression earlier. This would require a rethink of our clinical strategies. Unfortunately, too rapid changes in technology are sometimes detrimental in glaucoma since in a slowly progressive disease our patients need to be tested for years before we can detect slow rates of progression. While highlighting the importance of imaging keep in mind its limitations and the need for clinical judgment before any major diagnostic or therapeutic decisions are made.

Most of orbital lesions clinically present with proptosis, conjunctival congestion, chemosis, conjunctival bleeding, hemorrhage, pain, dropping of eyelids and restriction in eye movements. Due to these symptoms, patients come to the hospital early to seek the treatment.

For the patients with orbital lesions, a complete evaluation is essential to plan further diagnostic and treatment strategy. A complete high-resolution imaging with computed tomography (CT) or magnetic resonance imaging (MRI) has become most important investigations. Digital subtraction angiography has been considered the gold standard for vascular lesions including orbital lesions. Angiography can provide information about arterial blood supply, venous drainage, vessel caliber, collateral circulation, flow velocity, arteriovenous shunting, and presence of flow-related aneurysms which is essential for planning the interventions. CT and CT-angiography can provide excellent visualization of large and medium-sized blood vessels with dynamic information about blood flow to a vascular orbital lesion.

The various ophthalmic pathologies which can be diagnosed accurately and few of them can be treated using interventional radiological techniques are:

Surgery for these lesions is difficult due to high-risk of bleeding. The highest degree of success has been found when vascular malformations are treated by a multidisciplinary team. Image-guided therapy has proved highly effective with good to excellent results possible in 75-90% of patients.⁴ Interventional radiologists have taken a central role in the multidisciplinary team.

To treat vascular lesions of the orbit various routes had been tried with mixed results which are:

The necessary steps for safe performance of sclerotherapy include precise preprocedural lesion visualization and characterization, accurate needle placement, determination of the correct volume of sclerosing agent for injection, and real time monitoring of venous egress during the injection procedure.

For success of endovascular interventions of orbital lesion, detail knowledge of vascular anatomy, various materials used for procedure, embolic agents is very essential. Predicting the complications and their management is important to obtain good long-term results.