Welcome to the Division of Ophthalmology at the Medanta
This technique has been the mainstay of the diagnosis of retinal disorders for the last half century. A dye (Sodium fluorescein) is injected in one of the arm veins. The dye circulates through the blood to reach the eye veins. Photos of the eye are then taken using a special camera. This camera has a special filter that preferentially allows light rays coming from the dye to pass through. So the areas which have the dye are captured very clearly in the image of this camera. Serial photographs are taken to track the movement of the dye. In a normal person, the dye stays within the blood vessels of the retina and disappears from the eye in about 5 minutes.
In a number of retinal disorders, however, the dye leaks from the blood vessels into the surrounding tissue. Noticing the pattern and areas of dye leakage helps in the diagnosis and treatment of these disorders. Similarly, sometimes the dye fails to move beyond a certain point, suggesting an obstruction in the blood vessel at that site. Flourescein angiography is invaluable in the management of diabetic retinopathy, retinal vein occlusions, age related macular degeneration and a number of other retinal disorders.
This test has revolutionized the diagnosis and treatment of retinal disorders. OCT is nothing but a scan of the retina. It provides an enlarged, detailed image of different layers of the retina and its thickness in different parts. Seeing an OCT image of the retina is similar to observing the retina directly under a microscope. All layers of the retina and their specific changes from normal can be seen. The obvious practical advantage is that it can be seen in a living person, without having to dissect the eye.
The advantage of seeing all layers of the retina in real time cannot be overstated. Vision correlates directly with changes in the retina. OCT provides a direct assessment of what is wrong with the retina, and what can be done to correct it. This test has become indispensable in modern day retina practice. Current treatment guidelines for most retinal disorders are based on OCT measurements. Below are some images of a normal OCT scan and changes in different retinal disorders.
Macular edema in retinal vein occlusions
Hard exudates in diabetic retinopathy
RPE changes in dry age related macular degeneration
Choroidal neovascular membrane
Ultrasound of the eye is a very useful test for the assessment of the retinal anatomy in conditions where the retina cannot be directly seen e.g. cataract, bleeding in the eye. The principle is similar to ultrasound anywhere else in the body. An ultrasound probe sends supersonic sound waves into the eye. These waves are reflected from various structures of the eye. The reflected waves are detected and analysed, and projected in a pictorial form to give a two dimensional picture of the eye and different structures encountered by the sound waves. The frequency of sound waves used in eye ultrasound is different from that used in ultrasound elsewhere in the body. This frequency is specialized for detecting changes in small parts of the body.
Apart from being used where the retina cannot be directly seen, Ultrasound is also useful in the evaluation of retinal tumors and some types of uveitis. For retinal tumours, it helps to see the depth of the tumor and whether it is solid or hollow within. These aspects of a tumour cannot be made out on a direct retina examination. Also, in some retinal disorders like uveitis, there are some changes in the layer beneath the retina, which can be picked up by an ultrasound.
Normal eye ultrasound
Retinal tumour on ultrasound
Iron particle in the eye on ultrasound
Choroidal thickening on eye ultrasound
Accurate IOL power prediction is vital for patient satisfaction in modern day cataract surgery. Lenstar provides all necessary measurements required to take full advantage of the latest generation IOL prediction methods for improved refractive outcomes. New generation IOL power calculation methods such as Olsen and Barrett allow for excellent IOL prediction in short, average and long eyes with standard spherical or toric IOLs. Furthermore, EyeSuite a unique feature of Lenstar features a comprehensive set of post refractive IOL calculation formulae. It`s dual zone keratometry provides measurement of the axis and astigmatism, equivalent to the "Gold Standard" manual keratometry. The closely spaced 32 measurement point pattern improves precision, both delivering more data and minimizing the need for software data interpolation.
Anterior segment Optical coherence tomography (ASOCT) has proven to be an indispensable tool in the diagnosis and management of Corneal and Lens related disorders of the eye. ASOCT generates cross-sectional scans of the tissue to assist in analysis of the cornea, anterior chamber angle, iris and lens. It provides the treating physician with high quality images that are captured at a very high speed rate. ASOCT can assist in diagnosis and documentation of corneal conditions such as degenerations and dystrophies, as well as inflammatory pathologies. This technology can also be used to diagnose and manage corneal infiltrates, ulcers, dellen or scars. The depth and extent of the pathology can also be obtained by ASOCT imaging. It also has the capability to determine the depth and nature of foreign body or the presence of residue once removed.
Pentacam is one of the most precise and reliable diagnostic tool available for the measurement of cornea – the anterior portion of the eye. It uses Scheimpflug rotating high resolution camera technology to measure 138,000 points in 3 secs. It is considered to be a Gold standard test before any kind of surgery that is undertaken to remove glasses permanently. It detects minor abnormalities in the Cornea such as Forme Fruste Keratoconus and helps the doctor to screen out the cases which are not suitable for a LASIK procedure. It does so by analyzing both the front and back portion of the cornea. Screening out such patients helps in prevention of any long term complications. Pentacam is a non-contact procedure and has wide range of applications. It can be used to measure the density of the lens to detect cataract, measure the pupil diameter in patients who complain of excessive watering in presence of light, measure the angle in cases who have increased pressure in the eye and are suspected to have glaucoma. High resolution CCD camera and high end optical design generate brilliant Scheimpflug images to display and analyse.
Femtosecond laser has revolutionized the way we perform cataract surgery. All the patients require pupillary dilatation and topical anesthesia prior to surgery. This is followed by docking the eye, and imaging the anterior segment including the cataract. LenSx femtosecond laser system utilizes Fourier-domain optical coherence tomography (FD-OCT), imaging technology. Preprogrammed corneal incisions for temporal wound, paracentesis, and any optional limbal-relaxing incisions (LRIs) can be adjusted at this point to surgeon preference. No blades are required for the procedure. The pattern is then centered and the laser is activated. The Femtosecond laser causes tissue disruption with its near-infrared scanning pulse focused to 3 microns with an accuracy of 1 micron. The patient is then shifted to the other table and the cataract is extracted. This is followed by implantation of an artificial lens. The nature of the artificial lens that needs to be implanted is discussed with the patient prior to surgery.
The femtosecond laser has had a profound effect on refractive surgery and cataract surgery and, more recently on corneal transplantation. The results with femtosecond laser-assisted keratoplasty (FLAK) have shown this technique to provide increased resistance to wound leakage and excellent safety. FLAK also provides better outcomes in terms of astigmatism, visual acuity and early visual recovery than conventional penetrating keratoplasty. Femtosecond laser is appealing in corneal transplantation because of its ability to cut corneal tissue with greater precision and accuracy than hand trephination and to achieve interlocking edges in the graft-host interface that are not possible by hand. More advanced uses of the femtosecond laser are moving beyond full-thickness keratoplasty and into posterior lamellar incisions for Descemet’s stripping automated endothelial keratoplasty (DSAEK), Descemet’s membrane endothelial keratoplasty (DMEK), anterior lamellar keratoplasty (ALK) without sutures, deep anterior lamellar keratoplasty (DALK) and astigmatic keratotomies.
Keratoconus is a progressive ectatic disorder of the cornea which often presents with frequent change in glasses and sometimes decreased vision even with spectacles. Correcting the vision of these patients is a challenge because spectacles are unable to correct the irregular astigmatism and regular contact lenses may not be easily tolerated. Topography-guided custom ablation treatment (T-CAT) is a procedure of limited ablation of the cornea using excimer laser with the aim of regularizing the cornea, improving the quality of vision and also fitting of contact lens. The aim of the procedure is not to remove glasses permanently. Meticulous and methodical planning of the procedure is essential to ensure optimum results.
Collagen cross-linking (CXL) of the cornea involves the use of topical riboflavin combined with ultraviolet A (UVA) irradiation. It has demonstrated the potential for retarding the progression of Keratoconus and is widely performed across the world. It is often combined with procedures like Topography-guided custom ablation treatment (T-CAT) and Intrastromal ring placement (INTACS) for additional effect and better vision.
Lamellar corneal surgery is the selective replacement of patient`s diseased cornea while leaving behind the normal cornea intact. Anterior lamellar keratoplasty can correct all corneal opacities in patients who have normal endothelium (innermost part), rendering full thickness keratoplasty as the surgery of last resort. Unnecessarily transplanting donor endothelium predisposes the patient to a set of potential problems such as graft rejection, ie. Higher chances of failure of the body to accept the donor cornea.
Endothelial keratoplasty (EK) is a cornea transplant technique that is the preferred way to restore vision when the innermost cell layer of the cornea stops working properly from diseases such as Fuchs’ dystrophy, bullous keratopathy, iridocorneal endothelial (ICE) syndrome, or other endothelial disorders. This technique selectively replaces only the diseased layer of the cornea, leaving healthy areas intact.
Glaucoma is most commonly caused by a raised pressure in the eye (intraocular pressure). The eye is like a balloon where some fluid (aqueous humor) is getting produced by the ciliary processes and entering the eye and some fluid is exiting through a sieve like structure called the trabecular meshwork. If the outflow is obstructed then slowly the fluid builds up inside the eye and pressure rises. Most of the times medications can help reduce the pressure by either reducing fluid production or increasing outflow but sometimes when this is not enough to lower the eye pressure, a surgery needs to be done. The surgery is called a trabeculectomy or filtering surgery. In this procedure, a small part of the trabecular meshwork is cut and removed creating a hole (ostium) which allows the fluid accumulated in the eye to exit out into the space outside the globe but below the conjunctiva. This is done in a controlled manner by creating a flap of tissue (scleral flap) which keeps the ostium covered and allows only a little fluid out at a time. To prevent the ostium and subconjunctival space from closing, a special medicine called Mitomycin C is often applied in that area. The surgery takes about ½-1 hour and is done under topical or local or general anesthesia.
Intravitreal injections of Ranibizumab (Accentrix, Lucentis), Ozurdex and triamcinolone are routinely done at our centre, by doctors fully trained and certified in the procedure, and having an experience of over 5000 injections. We ensure the highest standards of quality, safety and efficacy in the administration of intravitreal drugs.
Retina laser is the gold standard in the treatment of proliferative diabetic retinopathy. Laser spots applied to the required area of the retina lead to shrinkage of neovessels that develop in proliferative diabetic retinopathy. Done in time, retina laser prevents the occurrence of vitreous hemorrhage from rupture of neovessels. Retina laser is also less commonly used in the treatment of diabetic macular edema. Low intensity laser burns are applied to the macula at prespecified spots, and lead to regression of macular edema. We at Medanta use the Alcon Purepoint laser machine, which is one of the most precise laser delivery systems available anywhere in the world. Our doctors have a combined experience of over 2000 retinal lasers. We guarantee accurate, convenient and safe laser treatment for diabetic retinopathy.
Surgery for diabetic retinopathy is the most challenging of all retinal surgeries, and requires tremendous expertise, innovation, skill and patience. Our retina specialty has surgeons thoroughly trained in such surgeries. The Alcon Constellation vitrectomy machine that we use is the single most advanced vitrectomy machine in the world today, preferred by leading eye centers the world over. Outcomes of surgery for diabetic retinopathy at our centre are at par with the best centres in the world.
Squint surgery is often required to correct different forms of strabismus/squint. The surgery entails operating on the 6 muscles which move the eye in different directions. The surgical procedure could either be done to weaken a muscle (recession surgery) or to strengthen a muscle (resection surgery). While there are various techniques described, recession and resection are the commonest procedures done. In recession, a muscle is disinserted from the globe and reattached a few millimeters behind depending upon the amount of weakening required. The muscle becomes lax and therefore weaker. In resection, the muscle is disinserted from its attachment on the eyeball, a small part of the tendon is cut and the muscle is reattached at the original site of attachment on the globe. The muscle becomes stretched and therefore stronger. The surgery may be done in either eye or both eyes and may require general or local anesthesia. The usual duration of the procedure is ½ to 1 hour.
It is a 100% blade-free LASIK procedure. It enables more precision and accuracy to achieve the perfect (6/6) vision or better. Femtosecond laser is a focusable infrared laser that uses ultra-short pulses in the hundred-femtosecond (100x10-15 seconds) duration range. The first clinical femtosecond laser in refractive surgery started in 1998. It has undergone many generation of changes and has increased its speed to provide the desired action in a matter of few seconds. It provides the advantages of smooth, precise & uniform flap with adjustable dimensions and sharp edge. Excimer laser is then used to reshape the cornea to enable best vision without the need of glasses in follow up. Femtosecond lasers has the benefit of providing stronger flap adhesion postoperatively.
Ptosis is one of the most challenging of the commonly encountered oculoplastic problems. A surgery is generally necessary to correct this condition. Most commonly the surgery is done through the skin route using small incisions which are hidden in the lid crease. The lid muscle which is responsible for elevating the upper lid ( the Levator Palpebrus superioris ) is subsequently tightened to elevate the lid. The procedure is done under local anaesthesia and lasts for around half an hour following which the patient is sent back home.
Frontalis sling is a special type of surgery that is required when the degree of ptosis is severe.It is generally performed for congenital ptosis. To achieve this, the eyelid is directly suspended to the brow using various materials. This creates a ‘sling’ from the frontalis muscle (brow) to the eyelid. Usually synthetic materials, such as suture or silicon are used.
Since its introduction in the early years of this century, External dacryocystorhinostomy (DCR) has been the "traditional" procedure most often relied upon for relief of epiphora (chronic tearing) and nasolacrimal duct obstruction in adults. It involves the formation of an anastomosis between the lacrimal sac and the nasal cavity.
Sometimes a tube might be placed in the anastomosis to keep the tract patent which is subsequently removed after 3-6 months. The surgery is done through a small incision in the tear trough line and subsequent dissection, bone removal and formation of the anastomosis. This procedure has a success rate of as high as 96 % in adult nasolacrimal duct obstructions.