Over the past decade, diagnostics in eye care services have undergone a radical transformation. Besides perfect clinical skill, emphasis is now laid on earliest possible detection of the patient’s medical condition. Accurate, elaborate and adequate diagnostic tests help to diagnose diseases and preferably sub-classify them regarding severity and treatability. Companion diagnostics have also been developed to preselect patients for specific treatments. It helps in a better understanding of the disease both by the treating doctor and the patient, besides helping in appropriate prognostication. It also helps to confirm that a person is free from disease.
Each minute detail in patients’ eyes is documented with the help of a slit lamp photography. It is practically impossible for a human mind to remember all details and hence appropriate documentation is a must. It helps in proper and long-term management of diseases. We have a special Topcon DSL camera integrated to our slit lamp for these purposes. This is a non-invasive, painless investigation with no discomfort to the patients.
Corneal topography is a non-invasive medical imaging technique for mapping the curvature of the cornea, the front part of the eye. Since the cornea is normally responsible for nearly 70% of the refractive power of the eye, its topography is of critical importance in determining the quality of vision. The three-dimensional map is therefore, a valuable aid to the examining ophthalmologist or optometrist and can assist in the diagnosis and treatment of a number of conditions like keratoconus, in planning refractive surgery such as LASIK and evaluation of its results or in assessing the fit of contact lenses. The report is in the form of a coloured print-out, which is very easy for the patient to understand. The procedure is carried out in seconds and is completely painless. At dristiCONE eye care, we routinely perform corneal topography for keratoconus screening and follow up, contact lens fitting, screening for LASIK and other refractive surgeries, for planning of Toric IOL and Toric ICL, LRI and post keratoplasty astigmatism. We use TOMEYwhich is among the most accurate corneal topographers. This is a non-invasive, painless investigation with no discomfort to the patients.
Many problems can arise when the eyes form an image of what they see. Ideally, light rays should be properly focused on the retina. In reality, the light is sometimes distorted by imperfections in the cornea and the lens. These distortions are called aberrations, and an aberrometer is used to measure them. It works on wavefront principle. In an eye with no aberrations, the wavefront will be flat, like a piece of paper. In an eye with imperfections, it will be bent and distorted. Like fingerprints, a wavefront map is unique to each patient. It gives a pictorial depiction of the various aberrations and their absolute value. This helps a great deal in customized LASIK surgery and personalized cataract surgery to choose the type of the intra-ocular lens.What is the kind of vision you have and can it be improved depends upon how aberrated is your eye system.
This is a non-invasive, painless investigation with no discomfort to the patients.
Out of the 5 layers of the cornea, the innermost layer of the cornea, endothelium, is most important to maintain the corneal transparency. Specular microscopy is used to view and record the image of the corneal endothelial cell layer non-invasively. It helps to access the structure and function of the corneal endothelium. The degree of endothelial cell loss from disease, trauma, chemical toxicity, etc can be documented as an increase in individual cell surface area and a decrease in the endothelial cell density for the cornea. Evaluation of the corneal endothelium is very import in some patients of endothelial diseases and in those who have had a complicated cataract surgery in the past. It is also important to measure the endothelium as a protocol before performing other routine eye surgeries like collagen cross-linking (CXL) for keratoconus and before implantation of an Implantable Collamer Lens (ICL) in the eye.
This is a non-invasive, painless investigation with no discomfort to the patients.
Optical coherence tomography gives micron level anatomical details and provides three-dimensional images of the structures in the eye. It is like the CT scan of the eye. The anterior segment OCT gives information about the cornea and anterior chamber angle. OCT helps measure the thickness of the cornea at various positions and also provides the corneal power at various points on the cornea. It is an invaluable tool to assess the position of the graft in endothelial keratoplasty patients. It also provides the most accurate anterior chamber depth that is important in deciding surgeries like ICL. At dristiCONE eye care we are using TOPCON OCT. The posterior segment OCT gives information about the retina, the fovea (part of the eye where the image forms) and the optic nerve head (part of the eye where the optic nerve leaves the eye). It is a very important tool to measure the foveal thickness, retinal nerve fibre layer thickness and the details about the intraretinal structures of the eye. Serial OCT measurements help to follow-up the patient and help to ascertain whether the patient is responding to the treatment like in case oocal LASERs or intravitreal injections. Retinal OCT finds wide application in macular conditions like diabetic macular edema, age related macular degeneration, Central serous chorioretinopathy, macular hole etc. Its completely non invasive and gives results in less than 10 seconds.
B scan ultrasonography is an important adjuvant for clinical assessment of various ocular and orbital diseases. It uses high-frequency sound waves which are transmitted from a probe into the eye. As the sound waves strike intraocular structures, they are reflected back to the probe and converted into an electric signal. The signal is subsequently reconstructed as an image and is used to make dynamic evaluation of the eye. B-scan USG is most useful when direct visualization of intraocular structures is difficult or impossible. In such cases, diagnostic B-scan ultrasound can accurately image intraocular structures and give valuable information on the status of the lens, vitreous, retina, choroid, and sclera. However, sometimes it is also indicated even in clear media as in case of intraocular tumors or or assessment of choroidal thickness in conditions like VKH. It is completely safe and non invasive diagnostic modality.
Fundus photography is the creation of a photograph of the interior surface of the eye, including the retina, optic nerve head, fovea and posterior pole (area of most retinal problems). Fundus photography is used for diagnosis of a disease (combined with retinal angiography), monitoring progression of a disease or in screening programs. It has the advantage of providing photo documentation for future reference. Fundus photography is performed by a fundus camera, which basically consists of a specialized low power microscope with an attached camera. Modern fundus photographs generally recreate considerably larger areas of the fundus than what can be seen at any one time with handheld ophthalmoscopes.
Fluorescent Fundus Aangiography (FFA) is a technique for examining the blood circulation of the retina and choroid using a fluorescent dye and a specialized camera. The test uses the dye tracing method. It involves injection of sodium fluorescein dye into the vein. The dye has a special fluorescence property which enables it to be traced by a specialzed camera as it moves in the arteries and the veins. As it appears in the retina and the choroid, serial photographs are taken and analysed. FFA is a very important diagnostic test for all retinal and choroidal problems that involve the blood circulation system. It helps in important decision making in treatment and follow-up in conditions like Diabetic Retinopathy, occlusions in the venous or arterial system and inflammation of the blood vessels (vasculitis). It is an invasive test and requires good kidney functions before it can be uptaken.
Fundus Autoluorescence (FAF) is a novel diagnostic modality that helps in topographic mapping of lipofuscin and other fluorophores, which usually accumulate in the retinal pigment epithelial layer (RPE). It gives information beyond conventional imaging techniques like fundus photography, FFA and OCT. Its edge lies in its non invasive nature. It finds application in various dystrophies like fundus flavimaculatus, Bests disease etc., disc drusen, chronic CSCR and also delineating activity in uveitic entities like serpiginous like choroiditis besides many others. Many conditions that earlier required repeat angiography can now be followed up by non invasiveautofluorescence testing.
Cataract surgery involves replacing the opacified normal crystalline lens with an intra-ocular lens. For minimal post-operative refractive error (glass power), accurate IOL power calculation is a must. Biometry involves assessment of power of the cornea and the length of the eyeball. With complex formulae, the IOL power is calculated. We use Huvitzautorefracto-keratometer and Tomey Corneal topographer for corneal power assessment. Axial length is measured using Biomedix A-scan.