Primary Health Care: Open Access

Opthalmology: A Brief Introduction

Tanay Shukla^{* *}Correspondence: Tanay Shukla, Department of Biotechnology ISBT, Shri Ramswaroop Memorial University, Lucknow, India, Email:

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Introduction

Ophthalmology is a surgical branch of medicine that focuses on the identification and treatment of conditions affecting the eyes. A doctor who has completed specialist training in both medical and surgical eye care is called an ophthalmologist. Ophthalmology specialists must do extra postgraduate residency training in that discipline after receiving their medical degrees. An integrated one-year internship that includes more comprehensive medical training in disciplines like internal medicine or general surgery may be part of this. Ophthalmologists use laser therapy, do surgery when necessary, and prescribe drugs to treat conditions such eye disorders. Primary and specialized medical and surgical eye care are both offered by ophthalmologists, at some time during their training, the majority of ophthalmologists take part in academic research on eye problems, and many go on to make research their profession.

Diseases treated by ophthalmologists

1. Cataract: A cataract refers to a cloudy area in the lens of the eye that leads to a decline in vision quality. Cataracts can affect one or both eyes and typically progress slowly. Common symptoms include seeing halos around lights, faded colors, blurred or double vision, sensitivity to bright lights, and difficulties with nighttime vision. Consequently, tasks such as reading, driving, and recognizing people can become problematic. Cataracts can also increase the risk of falls and contribute to feelings of depression. Globally, cataracts account for 33% of visual impairment and 51% of cases of blindness.

2. Excessive tearing (tear duct obstruction): Epiphora denotes an excessive flow of tears down the face that is not a result of regular crying. It arises from inadequate drainage of tears from the eyes, leading to tears streaming down the face instead of passing through the normal nasolacrimal system.

3. Thyroid eye disease: Thyroid eye disease, also known as Graves' ophthalmopathy, is an autoimmune inflammatory condition affecting the tissues around the eye and the eye socket. It is characterized by symptoms such as upper eyelid retraction, lid lag, swelling, redness (erythema), conjunctivitis, and protruding eyes (exophthalmos). This condition is more prevalent in individuals with Graves' disease compared to those with Hashimoto's thyroiditis or those who are euthyroid.

4. Eye tumors: Eye tumors can be benign or malignant (cancerous) growths that affect various parts of the eye. Primary eye cancer originates within the eye, while metastatic cancer spreads from other organs to the eye. Common sources of metastasis include breast and lung cancer. Less common sources include prostate, kidney, thyroid, skin, colon, and blood or bone marrow cancers.

5. Diabetic retinopathy: Diabetic retinopathy is a condition where diabetes mellitus causes damage to the retina, the light-sensitive tissue at the back of the eye. This condition can lead to visual impairment and vision loss if left untreated.

6. Dry eye syndrome: Dry eye syndrome, or keratoconjunctivitis sicca, is a disorder characterized by insufficient moisture in the eyes. Symptoms include dryness, inflammation, redness, discharge, blurry vision, and rapid eye fatigue. Symptoms can range from mild and occasional to severe and persistent. Dry eye syndrome can lead to changes in the eye's surface, affecting vision and potentially causing damage to the cornea.

7. Glaucoma: Glaucoma is a group of eye conditions that damage the optic nerve or retina, leading to vision loss. The most common form is open-angle glaucoma, where the fluid drainage angle remains open. Less common types include closed-angle glaucoma and normal-tension glaucoma.

8. Macular degeneration: Age-related Macular Degeneration (AMD) is a medical condition that can result in blurred or missing vision in the center of the visual field. It often starts without noticeable symptoms, but over time, it can cause a gradual decline in eyesight, affecting one or both eyes.

Diagnostic eye examination

1. Assessment of visual acuity: Visual Acuity (VA) measures an individual's ability to discern fine details, often describing the clarity of their eyesight. Both optical and neurological factors impact visual acuity. Optical variables influence the sharpness of the image on the retina, while neural factors encompass the health and functionality of the retina, neural connections in the brain, and the brain's interpretation center.

2. Ocular tonometry for intraocular pressure determination: Ocular tonometry is a technique employed by eye care professionals to measure intraocular pressure (IOP), which refers to the fluid pressure inside the eye. This test is particularly vital in assessing the risk of glaucoma. Normal ocular pressure typically ranges between 10 mmHg to 21 mmHg (13 hPa-28 hPa), and most tonometers are calibrated to gauge pressure in millimeters of mercury (mmHg).

3. Evaluation of extraocular motility and ocular alignment: The extraocular muscles, also known as extrinsic ocular muscles, comprise the seven muscles responsible for eye movement. Among them, the four recti muscles, superior and inferior oblique muscles, and levator palpebrae superioris control eye movement and eyelid elevation. The operation of these six muscles is contingent upon the eye's position during muscle contraction.

4.Slit lamp examination: A slit lamp, a crucial tool in ophthalmology and optometry, integrates a potent light source that can be focused to project a thin beam of light into the eye. It is paired with a bio microscope for examination purposes. This device facilitates the detailed assessment of structures like the cornea, iris, natural crystalline lens, eyelid, sclera, conjunctiva, and anterior and posterior segments of the eye. The binocular slitlamp examination provides a magnified, stereoscopic view of eye structures, aiding in the diagnosis of various eye conditions. An additional handheld lens may be utilized for retinal examination.

Specialized testing

1. Optical Coherence Tomography (OCT): Optical coherence tomography (OCT) utilizes low-coherence light to visualize optical scattering media like biological tissue in two and three dimensions with micrometer-level resolution. This technology finds applications in medical imaging and industrial nondestructive testing (NDT). Optical coherence tomography is built upon low-coherence interferometry, typically employing near-infrared light. Longer-wavelength light enables deeper penetration into scattering media. An alternative optical method, confocal microscopy, offers higher resolution but with shallower sample penetration.

2. Electroretinography (ERG): Electroretinography measures the electrical responses of various retinal cell types, including photoreceptors (rods and cones), inner retinal cells (bipolar and amacrine cells), and ganglion cells. Electrodes are placed either on the corneal surface (such as DTL silver/nylon fiber string or ERG jet) or around the eye's skin (using sensor strips) to assess retinal reactions.

3. Electrooculography (EOG): Electrooculography calculates the corneo-retinal standing potential, representing the electrical potential difference between the front and back of the human eye. The resulting signal is termed the electrooculogram. This method has two main applications: tracking eye movements and aiding in ophthalmological diagnostics.

4. Visual field testing: Visual field testing, performed through an eye examination, detects abnormalities in central and peripheral vision caused by various conditions such as glaucoma, stroke, pituitary disease, brain tumors, or neurological deficits. During clinical assessment, visual field testing involves presenting objects at different locations within the subject's visual field while maintaining a fixed gaze. Simple manual tools like the Amsler grid or tangent screen test can be employed. More specialized equipment, such as a perimeter, is used in advanced cases.

Opthalmic surgery

Ophthalmic surgery, also known as eye surgery or ocular surgery, involves a range of surgical procedures aimed at diagnosing, treating, or correcting various eye conditions and disorders.

These surgeries are performed by ophthalmologists, medical doctors who specialize in the field of ophthalmology. Ophthalmic surgery encompasses both traditional surgical techniques and advanced technologies, often aiming to improve or restore visual function and overall eye health. Here are some common types of ophthalmic surgeries:

1. Cataract surgery: This is one of the most common eye surgeries, involving the removal of a clouded lens (cataract) from the eye and its replacement with an artificial Intraocular Lens (IOL). Modern cataract surgery often employs minimally invasive techniques, such as phacoemulsification, which involves using ultrasound energy to break up the cataract for removal through a small incision.

2. Refractive surgery: Refractive surgery aims to correct refractive errors like myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. Popular refractive surgeries include LASIK (Laser-Assisted in Situ Keratomileusis) and PRK (Photorefractive Keratectomy), which reshape the cornea to improve vision.

3. Glaucoma surgery: Various surgical procedures, such as trabeculectomy and minimally invasive glaucoma surgery (MIGS), are performed to manage intraocular pressure and prevent further damage to the optic nerve caused by glaucoma.

4. Vitreo-retinal surgery: These surgeries address disorders of the retina and vitreous humor, such as retinal detachment, macular holes, and diabetic retinopathy. Procedures may involve removing or repairing damaged tissue and ensuring proper attachment of the retina.

5. Corneal transplant surgery: Also known as keratoplasty, this procedure involves replacing a damaged or diseased cornea with a healthy donor cornea to restore clear vision.

6. Oculoplastic Surgery: Oculoplastic surgery focuses on the eyelids, tear ducts, and the surrounding facial structures. Procedures may include eyelid lift (blepharoplasty), ptosis repair, and surgery for eyelid malpositions.

7. Strabismus surgery: This surgery corrects misalignment of the eyes (strabismus) by adjusting the extraocular muscles to improve eye coordination and alignment.

8. Orbital surgery: Orbital surgery addresses conditions affecting the eye socket, such as tumors, fractures, and inflammatory disorders.

9. Implantable contact lens surgery: This procedure involves implanting a contact lens-like device inside the eye to correct refractive errors.

10. Ocular surface surgery: These surgeries manage disorders of the cornea and conjunctiva, such as pterygium removal and amniotic membrane transplantation.