Search Results For astigmatism

Astigmatism

Astigmatism is an eye disorder that affects the curvature of the eye. This means that the shape of one’s eyes or the eye lens is irregular and this prevents light from being focused on to the retina properly. It is usually characterized by blurred vision.

Astigmatism occurs to most people today, but only to different extents. It can happen to a mild extent, which is not a cause for concern, but it can also have a negative effect on eye sight, blurring vision at times.

Astigmatism is a very common eye disorder, and it usually occurs along with other common eye disorders like Myopia (short-sightedness) and Hyperopia (far-sightedness). Together, these eye disorders are medically referred to as refractive errors.

Causes of Astigmatism

 Medical research has shown that astigmatism can occur even at birth, or after an eye injury, disease or surgery. It has also been identified to be hereditary.

The causes can be known based on the type of Astigmatism one has.

The two types of Astigmatism are:-

1. Corneal Astigmatism: This kind of astigmatism occurs when the cornea is curved improperly or imperfectly. Thus, in this case, the cornea has a distorted shape that prevents light rays from being refracted properly. Other cornea-related disorders like Keratoconus – wherein the cornea thins and degenerates gradually to become more conical in shape.

2. Lenticular Astigmatism: The other form of astigmatism deals with an imperfect or an improper eye lens. With the lens being curved imperfectly, the image that reaches the retina is imperfect, thus causing blurred vision. Some times lenticular astigmatism is seen in patients with diabetes. Fortunately, treatment of diabetes can also lead to reduction in astigmatism.

 

Symptoms of Astigmatism – Do you have Astigmatism?

Although diagnosis of the condition of Astigmatism is done through various eye check-ups and eye tests, astigmatism usually occurs with the onset of headaches, excessive squinting, fatigue, blurry vision, eyestrain, distorted vision and photophobia (sensitivity to light).

Diagnosis can be made with the help of visual acuity tests, regular eye tests, use of a Snellen Chart, Keratometer, a Keratoscope, or an astigmatic dial.

 

Treatment for Astigmatism

Astigmatism can be corrected with the prescription of corrective lenses (eye glasses or contact lenses) or refractive surgery.

Eyeglasses are the primary means to correct blurred vision brought upon by astigmatism. Cylindrical lenses are generally prescribed with a single lens to provide clarity of objects at all distances.

Contact Lenses and their effects: – While contact lenses are also prescribed by eye doctors and opticians alike, it is important to know the pros and cons of using contact lenses to cure astigmatism.

Regular cleaning and maintenance is required for contact lenses. The delicate nature of the lenses means that mishandling can lead to other eye disorders as well. However, it is still recommended as the best way to improve vision and correct astigmatism.

Astigmatism and Lasik/Laser Surgery: –

1. Photorefractive Keratectomy (PRK) is one of the laser surgery techniques used to treat astigmatism. Here, the protective layer or tissue of the cornea is removed and another laser changes the shape of the cornea. However, this laser treatment is known to be painful.

2. Laser in situ keratectomy (LASIK) is a recent development in the field of eye treatment technology. It has been favoured largely because it is known to cause the least amount of pain when compared to other corrective laser surgeries. It involves using a laser to make a thin cut into the cornea and then shaping the cornea with the help of an excimer laser.

Other measures include Orthokeratology and LASEK (Laser epithelial keratomileusis)

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Who needs LASIK 3X tra?

Who needs LASIK 3X tra™? Is it for everyone seeking LASIK? The combination of CXL and LASIK is indicated in all patients. LASIK 3X tra™ is indicated in the following cases:  Young LASIK candidates (less than 24 years of age); … Continue reading

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What is LASIK 3x tra?

LASIK 3X TRA™ LASIK 3X TRA™ is a new laser refractive procedure which combines LASIK and corneal Cross-linking. LASIK is a laser procedure done for those who seek to be free from spectacles and/ or contact lenses by treating their … Continue reading

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REQUIRED VISUAL STANDARDS FOR INDIAN ARMY, INDIAN NAVY, INDIAN AIR FORCE

After a candidate clears the SSB Interview, he/she is expected to undergo a Medical Examination held at the medical boards. Only the candidates who are declared fit by the medical authorities are eligible to join the Training Academy. In this article we are going to share details about Required Visual Standards for Indian Army, Indian Navy, Indian Air Force.

VISUAL STANDARDS FOR INDIAN ARMY

The eye sight requirement for the post of officer in Indian army is mentioned below:

  1. Uncorrected without glass – 6/12
  2. Corrected with glass – 6/6
  3. Limits of Myopia – 3.5
  4. Limits of Hypermetropia – +2.5
  5. Binocular vision III
  6. Limits of Colour Perception I
  7. A candidate should be able to read 6/6 in a distant vision chart with each eye with or without glasses. Myopia should not be more than 3.5D and hypermetropia not more than 3.5D including Astigmatism. For women candidates the minimum acceptable visual acuity are: Distant vision (corrected)better eye 6/6 worse 6/18, Myopia of not more than minus 5.5 including Astogination.
  8. Internal examination of the eye will be done by means of ophthalmoscope to rule out any disease of the eye. A candidate must have good binocular vision. The colour vision standard will be CP-III for Army A candidate should be able to recognise red and green colours.
  9. Candidates who have undergone or have the evidence of having undergone Radial Keratotomy, to improve the visual acuity, will be permanently rejected.
  10. Candidates who have undergone LASER Surgery for correction of refractive error will be considered for commission in Army if they fulfill following criteria :-
  11. Age more than 20 years.
  12. Uncomplicated stable LASIK/Excimer (PRK) laser procedure done for Myopia or Hypermetropia, with stable refraction for a period of six months after the procedure.
  13. A healthy retina.
  14. Corrected vision should be 6/6 in better eye and 6/9 in worse eye, with maximum residual refraction of + 1.50 in any meridian for myopia or hypermetropia.
  15. Axial length within permissible limits.

VISUAL STANDARDS FOR INDIAN AIR FORCE

  1. One must have 6/6 in one eye and 6/9 in other, which can be correctable to 6/6 only for hypermetropia.
  2. Near Vision must be N-5 each eye.

Near vision is determined using “Times Roman” type and is assessed at reading distance (30-50 cm) and at 100 cm. The 100-cm distance is important in the aircraft cockpit and similar environments and for users of CRT displays. When two values are shown, such as N5 and N14, the first value refers to the reading distance (30-50 cm) and the second value to the 100-cm distance.

Color Vision must be CP-1(ML T). Color Perception-1: The correct recognition of coloured lights shown through the paired apertures on the Holmes-Wright lantern at LOW BRIGHTNESS at 6 metres (20 feet) distance in complete darkness.

LASIK Surgery

LASIK Surgery for correction of vision is admissible in Transport and Helicopter streams of Short Service Commission (Flying Branch) If the following condition are fulfilled at the time of Air Force medical examination.

  1. LASIK Surgery should not have been carried out before the age of 20 years.
  2. The axial length of the eye should not be more than 25.5 mm as measured by IOL master.
  3. At least twelve months should have lapsed post uncomplicated stable LASIK. No history or evidence of any complication.
  4. The post LASIK corneal thickness as measured by a corneal pachymeter should not be less than 450 microns.
  5. Individuals with high refractive errors (>6D) prior to LASIK are to be excluded.
  6. Candidates must not suffer from colour or night blindness.
  7. Ocular Muscle Balance: Eyes should be well aligned and should have normal binocular vision. No manifest squint permissible. Convergence must be adequate. Ocular movements full and free Ocular muscle balance can be tested with the cover test, the Maddox rod or an approved vision tester.

At 6 meters

  • Exophoria 6 prism Diopters
  • Esophoria 6 prism Diopters
  • Hyperphoria 1 prism Diopters
  • Hypophoria 1 prism Diopters

At 33 cm

  • Exophoria 16 prism Diopters
  • Esophoria 6 prism Diopters
  • Hyperphoria 1 prism Diopters
  • Hypophoria 1 prism Diopters


VISUAL STANDARDS FOR INDIAN NAVY

(a) Uncorrected without glass 6/12

(b) Corrected with glass 6/6

(c) Limits of Myopia -1.5

(d) Limits of Hypermetropia +1.5

(e) Binocular vision Ill (f) Limits of Colour Perception

 

Source: http://ssbcrackexams.com/required-visual-standards-for-indian-army-indian-navy-indian-air-force/



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Indian Air Force Vision Medical Standards

One must have 6/6 in one eye and 6/9 in other, which can be correctable to 6/6 only for hypermetropia.

Vision Defects

  • Manifest hypermetropia must not exceed +2.0D Sphere.
  • No Myopia.
  • Astigmatism must be +0.75 D Cyl with +2.0 D maximum
  • Near Vision must be N-5 each eye.

Near vision is determined using “Times Roman” type and is assessed at reading distance (30-50 cm) and at 100 cm. The 100-cm distance is important in the aircraft cockpit and similar environments and for users of CRT displays. When two values are shown, such as N5 and N14, the first value refers to the reading distance (30-50 cm) and the second value to the 100-cm distance.

Color Vision must be CP-1(ML T). Color Perception-1: The correct recognition of coloured lights shown through the paired apertures on the Holmes-Wright lantern at LOW BRIGHTNESS at 6 metres (20 feet) distance in complete darkness.

LASIK Surgery

LASIK Surgery for correction of vision is admissible in Transport and Helicopter streams of Short Service Commission (Flying Branch) If the following condition are fulfilled at the time of Air Force medical examination.

  1. LASIK Surgery should not have been carried out before the age of 20 years.
  2. The axial length of the eye should not be more than 25.5 mm as measured by IOL master.
  3. At least twelve months should have lapsed post uncomplicated stable LASIK. No history or evidence of any complication.
  4. The post LASIK corneal thickness as measured by a corneal pachymeter should not be less than 450 microns.
  5. Individuals with high refractive errors (>6D) prior to LASIK are to be excluded.
  6. Candidates must not suffer from colour or night blindness.
  7. Ocular Muscle Balance: Eyes should be well aligned and should have normal binocular vision. No manifest squint permissible. Convergence must be adequate. Ocular movements full and free Ocular muscle balance can be tested with the cover test, the Maddox rod or an approved vision tester.

At 6 meters

Exophoria 6 prism Diopters

Esophoria 6 prism Diopters

Hyperphoria 1 prism Diopters

Hypophoria 1 prism Diopters

At 33 cm

Exophoria 16 prism Diopters

Esophoria 6 prism Diopters

Hyperphoria 1 prism Diopters

Hypophoria 1 prism Diopters

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Do powers or numbers come back after LASIK surgery

Do powers or numbers come back after LASIK surgery? How can we prevent this and what can be done if they do come back?

Let us say that you had LASIK surgery and achieved 6/6 or 20/20 vision, then many patients want to know how long does this result last? And are there any chances that their spectacle powers would regress?

LASIK surgery is a permanent treatment. What change it creates in the shape of the cornea is permanent.

However, the way you use your eyes is a dynamic process. Even if the LASIK was successful and you achieved 6/6 post procedure, to remain 20/20 there are certain basic guidelines that one must follow.

Remember that LASIK was done to achieve clear distant vision. If you end up doing a lot of near work, especially continuous hours of computer related work, then you stand the risk of again changing your distant prescription which is zero after LASIK and can shift by a small power of -0.50 D to -1.00 D if you end up straining your eyes for near work. Hence, in our centre at Shroff Eye, Dr Anand Shroff, our LASIK surgeon examines your eyes personally for a LASIK treatment and advises how you can avoid getting this regression, which may include specific steps of how to sit in front of a computer screen and use computer anti fatigue glasses specific to your viewing distance. This is taught to you post LASIK, at our centre.

However, other than the most common reason for shift of powers, which is computers, there are other factors which also play a role in eye health.  Vision can deteriorate if any other event happens inside the eyes, example the start of a cataract or retinal issue or need for reading glasses (presbyopia) which is a natural aging process in the eyes. Although this is totally unrelated to LASIK, and would have happened with the same possibility when you use glasses or contact lenses, many link it to a LASIK done many years ago. This is not true. The start of any internal eye disease is not linked to your LASIK.

In women, it is also important to mention the use of hormones for treating acne or even infertility etc. In such times, hormones in very rare cases may also cause a shift in myopia.

In those with very high myopia or high astigmatism or cylindrical powers, we prepare them with the small possibility of needing a fine tuning or retreatment procedure, also called enhancement. This is usually done not before 3 months of the LASIK, giving enough time for the corneal healing to be complete.  Also, this re treatment does not mean repeating all steps done the first time, but in most cases just needs specific instruments to lift the previously prepared flap and a very short laser application to remove the power. In those where the flap lifting is doubtful, a PRK procedure can be done as a surface treatment.

Therefore, it is important to choose a primary LASIK treatment with an advanced laser, such as what we use at Shroff Eye, the 500 Hz Wavelight laser that helps score over others as it has corneal tissue saving capacity. Hence it is possible to retreat whenever required.
In many cases, people who experience minor number changes after LASIK are not bothered by the small power and do not feel the need for wearing glasses, except for specific tasks like night driving, where it is used more for safety. Some choose to undergo a retreatment whenever possible, for example the rate of re treatment in our LASIK centre with Dr Anand Shroff is less than 0.4% of our cases and most often the fee is not charged again.

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Technical differences between various excimer lasers

 

Most excimer lasers-

Wavefront LASIK

Ex- 500 – Contoura™ LASIK with Occulyzer + Topolyser Vario

(only at Shroff Eye, Mumbai)

 
1) Synchronized eye trackers @ 500 Hz = 6 millisecs response time @1050 Hz

Laser falls on programmed target

Therefore feedback time which is a response time of 2 millisecs
2)                        – 3  times sturdier laser lead With Topolyzer Vario

→ Cyclotorsion for cylinder

≥  -1.5D

3) open to environment Sealed optics stable energy Auto neuro tracking and infrared camera in both topolyser and the laser. Also has a pupillometer for night vision issues. = Contura vision. Detects iris landmarks. Any from vertical to supine position means that eye rotates; therefore the compensation needs to be done. No human error as no punching of work. It is transferred software to software. The diagnostic and live image software overlaps to find differences and adjust those differences

 

 

Ex 500 Mel 90 Mel 80
1) 500 Hz 1) 250→500Hz 1) 250Hz
2) Wavefront optimized treatments. Does not induce higher order aberrations and maintains spherical profile 2) Becomes oblate and induces spherical aberrations

 

 

 

2) Becomes oblate and induces spherical aberrations

 

 

3) ASA + Corneal saving

FDA approved -12.00D

-14.00 D internal

CE approval.

Astigmatism ±5.00 D

±6.00 D internal

 

Optical zone 8.5 mm

True optical zone 6.5mm

 

 

AAA algorithim claims to do ASA + corneal save

Not FDA approved

 

 

 

 

 

 

ASA and tissue saving

Maintain natural aspherically

 

more corneal aberrations

 

though issue saving option

You will save tissue but not maintaining asphericity

6 D eye tracker

6 sigma multispectial eye tracker

 

3D tracker

 

3D tracker

 

With slit lamp

Online Pachymetry

No integrated slit lamp

No online Pachymetry

 

 

No integrated slit lamp

No online Pachymetry

 

 

Topography linked treatments were used earlier on cases who had some laser treatment done on their cornea. Not used as Primary treatment.

But now with Contoura, it is the only FDA approved Topography treatment to be used as a primary LASIK treatment.

Topography LASIK address the corneal irregularities as most aberrations are from cornea.

 

 

With contura one can expect gain in line of acuity in 30% cases.

At Shroff Eye we have the diagnostics which no centre has ie. the Occulyzer plus the Topolyser Vario. This is important to detect early Keraconus.

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Testimonials

LASIK  Testimonials What our patients say about us…     To start with, I am doing very well post the FEMTO LASIK I underwent at Shroff Eye Hospial, Mumbai in Feb 2018. It’s over 3 months and the post care … Continue reading

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