Videokeratographs are modern topographers which use a bowl containing a pattern of luminous concentric rings projected onto the cornea (Placido disk principle) to acquire corneal topography data.

Orbscan II also utilizes a beam of light that is shone across the cornea in order to image the elevation of the cornea's posterior and anterior surfaces. Moreover, this technique makes it possible to measure the corneal thickness at every point of the corneal surface, as well as the depth of the anterior chamber. This instrument is therefore particularly useful in refractive surgery and for differential diagnosis of corneal abnormalities. The Orbscan technology has revolutionized topography by introducing a new three-dimensional element into corneal exploration.

Topography and interpretation software have evolved rapidly over the past few years. These instruments have become essential tools, not only for 10the assessment of patients considered for refractive surgery, but also for confirming a pathological diagnosis or for easy fitting of corneal lenses. These instruments also provide an overview of the corneal topography, making it possible to determine its eccentricity or its degree of peripheral flattening.

Corneal topography enables us to detect abnormalities, and to document and monitor the progress of many clinical cases such as corneal surface irregularities due to pathology or a traumatism, keratoconus, dystrophy or corneal degeneration, irregular astigmatism, halo complaints, glare and monocular diplopia. Topography is useful in the adaptation of contact lenses, not only for patients suffering from keratoconus, but also in cases of unexplained decentering of corneal lenses.

For patients considered for refractive surgery, corneal topography is essential to exclude patients with an abnormal corneal topography. With some topography devices, one can simulate LASER ablation to obtain an idea of the post-operative corneal topography according to the ablation zone and ablation depth chosen.

This method is also used following surgery to visualize the effect of the ablation and to monitor the healing process. In addition it is possible to eliminate irregularities of the corneal surface, to compare the diameter and position of the ablation zone with the diameter of the pupils, and to visualize the effect of surgery on the posterior surface of the cornea, as well as on corneal thickness.11

Topography will also play a role in researching multi-zone ablation profiles for the correction of presbyopia – a forthcoming challenge in the field of ophthalmic surgery.

I do not want to close without paying tribute to the Agarwal family for their pioneering work in eye surgery through the last five generations. In this foreword I particularly wish to congratulate Dr J Agarwal, the father of my friend Amar, who has received the highest civil distinction from the Indian Federation Padma Bhushan for his outstanding work in the field of ophthalmology.

Quite obviously it is our thinking which is different, when some amongst us can reach the heights of scientific methodology, we can too. All we need to do is to have a method in analysis of thought. Very often the thought that comes to us we identify with it and our lost in the mundane. In fact the sages would even advice in not identifying with the body or the mind and to go into a no thought stage. The continuous chatter in our brains however never lets up, and yet should you go down to analyze–it comes from only six major root causes they are need, habit, environmental conditions, imposition by somebody, heredity and from the divine.

All the others are in somehow or the other taking up all our time, when and if we do go into a stage of meditation called where there is no thought arising, then a small voice will give some clear instructions14 and this will usually be targeted at bringing forth a simple law of nature. It was this that made the great scientists different from the rest as they were able to decipher these thoughts and then prove the point across through laborious work in the laboratory.

The study of the mountains and the lakes gives us the topography of the land, and it was thus scientists searching for better and better means to record the topography of the cornea that lead to the corneal topography exercise becoming an invaluable tool in the eye surgeon's armamentarium. This book has been made through the exercise of analyzing thought and letting it work towards constructive scientific achievement however big or small.

The difference dear reader is to never let up with the luxury of letting the thought take you within its maze, the major breakthrough is in analyzing it and making sure that it works towards your success, your realization, since every triumph of yours is actually a triumph of humanity. This is the major advantage we as scientists and people of medicine have, that everything we do is towards the upliftment of human suffering, towards the realization of some new simple law of nature.